diff --git a/configure.ac b/configure.ac
index 67f5c7d15..164d5b304 100644
--- a/configure.ac
+++ b/configure.ac
@@ -360,32 +360,6 @@ AC_DEFUN([_MY_CXX_CHECK_OPT],
     _MY_CXX_CHECK_IFELSE($2, $1="$$1 $2")
    ])
 
-# _MY_CXX_CHECK_IS_CLANG_VERSION(variable,min-version,max-version)
-# Check if the C++ compiler is Clang, with version >= min-version and
-# < max-version. Versions are given as 'major.minor.patch'. An empty
-# bound means unbounded at that end.
-# Set variable to yes or no accordingly.
-AC_DEFUN([_MY_CXX_CHECK_IS_CLANG_VERSION],
-   [AC_MSG_CHECKING([whether $CXX is Clang >= m4_default([$2],[any]) and < m4_default([$3],[any])])
-    AC_COMPILE_IFELSE(
-       [AC_LANG_SOURCE([[
-#if !defined(__clang__)
-# error "Not Clang"
-#endif
-#define _MY_VER(maj, min, pat) ((maj) * 1000000 + (min) * 1000 + (pat))
-#define _MY_CLANG_VER _MY_VER(__clang_major__, __clang_minor__, __clang_patchlevel__)
-#if _MY_CLANG_VER < _MY_VER(]]m4_quote(m4_translit(m4_default([$2],[0.0.0]),[.],[,]))[[)
-# error "Clang older than min-version"
-#endif
-#if _MY_CLANG_VER >= _MY_VER(]]m4_quote(m4_translit(m4_default([$3],[99999.0.0]),[.],[,]))[[)
-# error "Clang not older than max-version"
-#endif
-]])],
-       [$1=yes],
-       [$1=no])
-    AC_MSG_RESULT($$1)
-   ])
-
 AC_DEFUN([_MY_CXX_CHECK_CORO_SET],
    [# _MY_CXX_CHECK_CORO_SET(variable,option)
     # Check if compiler supports coroutines with specific option. If it does,
@@ -471,8 +445,6 @@ AC_DEFUN([_MY_LDLIBS_CHECK_SET],
     fi
    ])
 
-_MY_CXX_CHECK_IS_CLANG_VERSION(CXX_IS_CLANG_18, 18.0.0, 19.0.0)
-
 # Add the coverage flags early as they influence later checks.
 if test "$CFG_WITH_DEV_GCOV" = "yes"; then
   CFG_GCOV_CXX="$CXX"
@@ -658,13 +630,7 @@ m4_foreach([cflag],[
     # CMake will test what flags work itself, so pass all flags through to it
     CFG_CXX_FLAGS_CMAKE="$CFG_CXX_FLAGS_CMAKE cflag"
     ])
-if test "$CXX_IS_CLANG_18" = "yes"; then
-  # Clang 18 only: disable the SLP vectorizer; see verilator/verilator#8379
-  _MY_CXX_CHECK_OPT(CFG_CXXFLAGS_ALWAYS,-fno-slp-vectorize)
-  CFG_CXX_FLAGS_CMAKE="$CFG_CXX_FLAGS_CMAKE -fno-slp-vectorize"
-fi
 AC_SUBST(CFG_CXXFLAGS_NO_UNUSED)
-AC_SUBST(CFG_CXXFLAGS_ALWAYS)
 AC_SUBST(CFG_CXX_FLAGS_CMAKE)
 
 # Find multithread linker flags
diff --git a/docs/guide/connecting.rst b/docs/guide/connecting.rst
index 3d1fafd5d..eb1f997a4 100644
--- a/docs/guide/connecting.rst
+++ b/docs/guide/connecting.rst
@@ -40,6 +40,30 @@ model:
   internals, including ``/* verilator public_flat */`` items.
 
 
+.. _model header include macros:
+
+Model Header Include Macros
+---------------------------
+
+Code compiled with the generated :file:`{prefix}.mk`, or with the CMake
+``verilate()`` command, gets preprocessor macros that expand to the model
+header includes, so user C++ need not hard-code the :vlopt:`--prefix`:
+
+.. code-block:: C++
+
+   #include VM_PREFIX_INCLUDE      // e.g. <Vtop.h>
+   #include VM_PREFIX_INCLUDE_DPI  // e.g. <Vtop__Dpi.h>
+
+``VM_PREFIX_INCLUDE_DPI`` is defined only when Verilator generates the
+:file:`{prefix}__Dpi.h` header, which is the case for designs with DPI and
+also for public-signal access such as :vlopt:`--public-flat-rw`. Using it
+otherwise is a compile-time error.
+
+A target built from several models defines each macro once, naming the
+first model, as one target has one set of preprocessor definitions. Code
+that must reach a second model's header names it directly.
+
+
 .. _porting from pre 4.210:
 
 Model interface changes in version 4.210
@@ -207,6 +231,9 @@ command line, or the link), you'd then:
    #include "Vour__Dpi.h"
    int add(int a, int b) { return a+b; }
 
+Rather than hard-coding the prefix, ``#include VM_PREFIX_INCLUDE_DPI`` may
+be used instead; see :ref:`Model Header Include Macros`.
+
 
 DPI System Task/Functions
 -------------------------
diff --git a/include/verilated.mk.in b/include/verilated.mk.in
index 542ea001e..0c6dbb33d 100644
--- a/include/verilated.mk.in
+++ b/include/verilated.mk.in
@@ -38,8 +38,6 @@ CFG_CXXFLAGS_STD = @CFG_CXXFLAGS_STD@
 CFG_CXXFLAGS_STD_NEWEST = @CFG_CXXFLAGS_STD_NEWEST@
 # Compiler flags to use to turn off unused and generated code warnings, such as -Wno-div-by-zero
 CFG_CXXFLAGS_NO_UNUSED = @CFG_CXXFLAGS_NO_UNUSED@
-# Compiler flags to always use
-CFG_CXXFLAGS_ALWAYS = @CFG_CXXFLAGS_ALWAYS@
 # Compiler flags that turn on extra warnings
 CFG_CXXFLAGS_WEXTRA = @CFG_CXXFLAGS_WEXTRA@
 # Compiler flags that enable coroutine support
@@ -100,7 +98,16 @@ VK_CPPFLAGS_ALWAYS += \
   -DVM_TRACE_SAIF=$(VM_TRACE_SAIF) \
   -DVM_VPI=$(VM_VPI) \
   $(CFG_CXXFLAGS_NO_UNUSED) \
-  $(CFG_CXXFLAGS_ALWAYS) \
+
+# Left undefined when there is no generated model, so misuse fails at compile time
+ifneq ($(VM_PREFIX_INCLUDE),)
+  VK_CPPFLAGS_ALWAYS += -DVM_PREFIX_INCLUDE="$(VM_PREFIX_INCLUDE)"
+endif
+
+# Left undefined when the design has no DPI, so misuse fails at compile time
+ifneq ($(VM_PREFIX_INCLUDE_DPI),)
+  VK_CPPFLAGS_ALWAYS += -DVM_PREFIX_INCLUDE_DPI="$(VM_PREFIX_INCLUDE_DPI)"
+endif
 
 ifeq ($(CFG_WITH_CCWARN),yes)  # Local... Else don't burden users
   VK_CPPFLAGS_WALL += -Wall $(CFG_CXXFLAGS_WEXTRA) -Werror
diff --git a/src/V3EmitMk.cpp b/src/V3EmitMk.cpp
index 891f0b6fd..3a3e560f2 100644
--- a/src/V3EmitMk.cpp
+++ b/src/V3EmitMk.cpp
@@ -664,10 +664,17 @@ public:
         of.putSet("VM_SC_TARGET_ARCH", V3Options::getenvSYSTEMC_ARCH());
 
         of.puts("\n### Vars...\n");
-        of.puts("# Design prefix (from --prefix)\n");
-        of.putSet("VM_PREFIX", v3Global.opt.prefix());
         of.puts("# Module prefix (from --prefix)\n");
         of.putSet("VM_MODPREFIX", v3Global.opt.modPrefix());
+        of.puts("# Design prefix (from --prefix)\n");
+        of.putSet("VM_PREFIX", v3Global.opt.prefix());
+        of.puts("# Design header include, for '#include VM_PREFIX_INCLUDE' (from --prefix)\n");
+        of.putSet("VM_PREFIX_INCLUDE", "<" + v3Global.opt.prefix() + ".h>");
+        if (v3Global.dpi()) {
+            of.puts("# DPI header include, for '#include VM_PREFIX_INCLUDE_DPI';"
+                    " undefined if no DPI\n");
+            of.putSet("VM_PREFIX_INCLUDE_DPI", "<" + v3Global.opt.prefix() + "__Dpi.h>");
+        }
 
         of.puts("# User CFLAGS (from -CFLAGS on Verilator command line)\n");
         of.puts("VM_USER_CFLAGS = \\\n");
diff --git a/src/V3EmitMkJson.cpp b/src/V3EmitMkJson.cpp
index 042787ea8..a63eed840 100644
--- a/src/V3EmitMkJson.cpp
+++ b/src/V3EmitMkJson.cpp
@@ -94,6 +94,7 @@ class V3EmitMkJsonEmitter final {
             .putList("ldflags", v3Global.opt.ldLibs())
             .put("system_c", v3Global.opt.systemC())
             .put("coverage", v3Global.opt.coverage())
+            .put("dpi", v3Global.dpi())
             .put("use_timing", v3Global.usesTiming())
             .put("threads", v3Global.opt.threads())
             .put("trace", v3Global.opt.trace())
diff --git a/test_regress/CMakeLists.txt b/test_regress/CMakeLists.txt
index 5934287ba..704c38d82 100644
--- a/test_regress/CMakeLists.txt
+++ b/test_regress/CMakeLists.txt
@@ -137,6 +137,5 @@ target_compile_definitions(
     PRIVATE
         "TEST_OBJ_DIR=${CMAKE_CURRENT_BINARY_DIR}"
         "VM_PREFIX=${TEST_PREFIX}"
-        "VM_PREFIX_INCLUDE=<${TEST_PREFIX}.h>"
         "${TEST_NAME_UC}"
 )
diff --git a/test_regress/Makefile_obj b/test_regress/Makefile_obj
index b7c6c5af1..f5ffe64fb 100644
--- a/test_regress/Makefile_obj
+++ b/test_regress/Makefile_obj
@@ -30,7 +30,6 @@ CPPFLAGS += -DVL_DEBUG=1
 # Needed by tracing routines
 CPPFLAGS += -DTEST_OBJ_DIR=$(TEST_OBJ_DIR)
 CPPFLAGS += -DVM_PREFIX=$(VM_PREFIX)
-CPPFLAGS += -DVM_PREFIX_INCLUDE="<$(VM_PREFIX).h>"
 CPPFLAGS += -DVM_PREFIX_ROOT_INCLUDE="<$(VM_PREFIX)___024root.h>"
 CPPFLAGS += $(CPPFLAGS_DRIVER)
 CPPFLAGS += $(CPPFLAGS_DRIVER2)
diff --git a/test_regress/t/t_dpi_accessors.cpp b/test_regress/t/t_dpi_accessors.cpp
index 6c034d0f1..18b7228ae 100644
--- a/test_regress/t/t_dpi_accessors.cpp
+++ b/test_regress/t/t_dpi_accessors.cpp
@@ -12,7 +12,7 @@
 //*************************************************************************
 
 #include "Vt_dpi_accessors.h"
-#include "Vt_dpi_accessors__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 #include <iomanip>
diff --git a/test_regress/t/t_dpi_arg_inout_type.cpp b/test_regress/t/t_dpi_arg_inout_type.cpp
index 8f67abf3d..0684b562f 100644
--- a/test_regress/t/t_dpi_arg_inout_type.cpp
+++ b/test_regress/t/t_dpi_arg_inout_type.cpp
@@ -23,7 +23,7 @@
 #include "svdpi.h"
 
 #if defined(VERILATOR)  // Verilator
-# include "Vt_dpi_arg_inout_type__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 typedef long long sv_longint_t;
 typedef unsigned long long sv_longint_unsigned_t;
 # define NO_SHORTREAL
diff --git a/test_regress/t/t_dpi_arg_inout_unpack.cpp b/test_regress/t/t_dpi_arg_inout_unpack.cpp
index d1cb24965..e3ace43af 100644
--- a/test_regress/t/t_dpi_arg_inout_unpack.cpp
+++ b/test_regress/t/t_dpi_arg_inout_unpack.cpp
@@ -25,7 +25,7 @@
 #include "svdpi.h"
 
 #if defined(VERILATOR)  // Verilator
-# include "Vt_dpi_arg_inout_unpack__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 typedef long long sv_longint_t;
 typedef unsigned long long sv_longint_unsigned_t;
 # define NO_SHORTREAL
diff --git a/test_regress/t/t_dpi_arg_input_type.cpp b/test_regress/t/t_dpi_arg_input_type.cpp
index 1b565fc8d..9ee3bee5d 100644
--- a/test_regress/t/t_dpi_arg_input_type.cpp
+++ b/test_regress/t/t_dpi_arg_input_type.cpp
@@ -23,7 +23,7 @@
 #include "svdpi.h"
 
 #if defined(VERILATOR)  // Verilator
-# include "Vt_dpi_arg_input_type__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 typedef long long sv_longint_t;
 typedef unsigned long long sv_longint_unsigned_t;
 # define NO_SHORTREAL
diff --git a/test_regress/t/t_dpi_arg_input_unpack.cpp b/test_regress/t/t_dpi_arg_input_unpack.cpp
index 1ec2c3ed9..8e98c2938 100644
--- a/test_regress/t/t_dpi_arg_input_unpack.cpp
+++ b/test_regress/t/t_dpi_arg_input_unpack.cpp
@@ -25,7 +25,7 @@
 #include "svdpi.h"
 
 #if defined(VERILATOR)  // Verilator
-# include "Vt_dpi_arg_input_unpack__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 typedef long long sv_longint_t;
 typedef unsigned long long sv_longint_unsigned_t;
 typedef const void** sv_chandle_array_ptr_t;
diff --git a/test_regress/t/t_dpi_arg_output_type.cpp b/test_regress/t/t_dpi_arg_output_type.cpp
index a9092561d..24430f3d1 100644
--- a/test_regress/t/t_dpi_arg_output_type.cpp
+++ b/test_regress/t/t_dpi_arg_output_type.cpp
@@ -23,7 +23,7 @@
 #include "svdpi.h"
 
 #if defined(VERILATOR)  // Verilator
-# include "Vt_dpi_arg_output_type__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 typedef long long sv_longint_t;
 typedef unsigned long long sv_longint_unsigned_t;
 # define NO_SHORTREAL
diff --git a/test_regress/t/t_dpi_arg_output_unpack.cpp b/test_regress/t/t_dpi_arg_output_unpack.cpp
index 22ae61241..eafe892f6 100644
--- a/test_regress/t/t_dpi_arg_output_unpack.cpp
+++ b/test_regress/t/t_dpi_arg_output_unpack.cpp
@@ -25,7 +25,7 @@
 #include "svdpi.h"
 
 #if defined(VERILATOR)  // Verilator
-# include "Vt_dpi_arg_output_unpack__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 typedef long long sv_longint_t;
 typedef unsigned long long sv_longint_unsigned_t;
 # define NO_SHORTREAL
diff --git a/test_regress/t/t_dpi_context_c.cpp b/test_regress/t/t_dpi_context_c.cpp
index 9ca792a0c..3a58bd086 100644
--- a/test_regress/t/t_dpi_context_c.cpp
+++ b/test_regress/t/t_dpi_context_c.cpp
@@ -17,11 +17,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# ifdef T_DPI_CONTEXT_NOOPT
-#  include "Vt_dpi_context_noopt__Dpi.h"
-# else
-#  include "Vt_dpi_context__Dpi.h"
-# endif
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(CADENCE)
diff --git a/test_regress/t/t_dpi_decl.cpp b/test_regress/t/t_dpi_decl.cpp
index 5cf783a39..eea64595c 100644
--- a/test_regress/t/t_dpi_decl.cpp
+++ b/test_regress/t/t_dpi_decl.cpp
@@ -8,7 +8,7 @@
 // SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
 //
 //*************************************************************************
-#include "Vt_dpi_decl__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 
 char* func(const char* arg) {
     static char str[] = "abc";
diff --git a/test_regress/t/t_dpi_display_c.cpp b/test_regress/t/t_dpi_display_c.cpp
index b93fa7f1c..638c4fe2e 100644
--- a/test_regress/t/t_dpi_display_c.cpp
+++ b/test_regress/t/t_dpi_display_c.cpp
@@ -17,7 +17,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_display__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(CADENCE)
diff --git a/test_regress/t/t_dpi_export_c.cpp b/test_regress/t/t_dpi_export_c.cpp
index cbc479f04..39e0669cc 100644
--- a/test_regress/t/t_dpi_export_c.cpp
+++ b/test_regress/t/t_dpi_export_c.cpp
@@ -19,11 +19,7 @@
 //======================================================================
 
 #if defined(VERILATOR)
-#ifdef T_DPI_EXPORT_NOOPT
-#include "Vt_dpi_export_noopt__Dpi.h"
-#else
-#include "Vt_dpi_export__Dpi.h"
-#endif
+#include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 #include "../vc_hdrs.h"
 #elif defined(CADENCE)
diff --git a/test_regress/t/t_dpi_export_context2_bad.cpp b/test_regress/t/t_dpi_export_context2_bad.cpp
index b597865e6..e39b912f1 100644
--- a/test_regress/t/t_dpi_export_context2_bad.cpp
+++ b/test_regress/t/t_dpi_export_context2_bad.cpp
@@ -11,7 +11,7 @@
 
 //======================================================================
 
-#include "Vt_dpi_export_context2_bad__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 
 //======================================================================
 
diff --git a/test_regress/t/t_dpi_export_context_bad.cpp b/test_regress/t/t_dpi_export_context_bad.cpp
index c563f0f8a..fa5e7bd5b 100644
--- a/test_regress/t/t_dpi_export_context_bad.cpp
+++ b/test_regress/t/t_dpi_export_context_bad.cpp
@@ -13,7 +13,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_export_context_bad__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(CADENCE)
diff --git a/test_regress/t/t_dpi_export_scope_bad.cpp b/test_regress/t/t_dpi_export_scope_bad.cpp
index 0fba1bce5..f49f83ba3 100644
--- a/test_regress/t/t_dpi_export_scope_bad.cpp
+++ b/test_regress/t/t_dpi_export_scope_bad.cpp
@@ -10,7 +10,7 @@
 
 //======================================================================
 
-#include "Vt_dpi_export_scope_bad__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 
 #ifdef NEED_EXTERNS
 extern "C" {
diff --git a/test_regress/t/t_dpi_export_scope_flat.cpp b/test_regress/t/t_dpi_export_scope_flat.cpp
index d444e9fda..f49f83ba3 100644
--- a/test_regress/t/t_dpi_export_scope_flat.cpp
+++ b/test_regress/t/t_dpi_export_scope_flat.cpp
@@ -10,7 +10,7 @@
 
 //======================================================================
 
-#include "Vt_dpi_export_scope_flat__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 
 #ifdef NEED_EXTERNS
 extern "C" {
diff --git a/test_regress/t/t_dpi_if_cond_c.cpp b/test_regress/t/t_dpi_if_cond_c.cpp
index 0e0324a41..63ed843e7 100644
--- a/test_regress/t/t_dpi_if_cond_c.cpp
+++ b/test_regress/t/t_dpi_if_cond_c.cpp
@@ -21,7 +21,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_if_cond__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(NC)
diff --git a/test_regress/t/t_dpi_imp_gen_c.cpp b/test_regress/t/t_dpi_imp_gen_c.cpp
index 79bd06c16..f767813c5 100644
--- a/test_regress/t/t_dpi_imp_gen_c.cpp
+++ b/test_regress/t/t_dpi_imp_gen_c.cpp
@@ -18,7 +18,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_imp_gen__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(CADENCE)
diff --git a/test_regress/t/t_dpi_import_c.cpp b/test_regress/t/t_dpi_import_c.cpp
index 52bcb2d1f..b671d52ef 100644
--- a/test_regress/t/t_dpi_import_c.cpp
+++ b/test_regress/t/t_dpi_import_c.cpp
@@ -18,7 +18,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_import__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(CADENCE)
diff --git a/test_regress/t/t_dpi_inline_new.cpp b/test_regress/t/t_dpi_inline_new.cpp
index 869e2bec1..e1e2d7d0b 100644
--- a/test_regress/t/t_dpi_inline_new.cpp
+++ b/test_regress/t/t_dpi_inline_new.cpp
@@ -6,7 +6,7 @@
 
 // Include the Verilator-generated DPI header so the C prototype matches
 // the SystemVerilog import expectations.
-#include "Vt_dpi_inline_new__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/test_regress/t/t_dpi_lib_c.cpp b/test_regress/t/t_dpi_lib_c.cpp
index 688cb5d65..352d30419 100644
--- a/test_regress/t/t_dpi_lib_c.cpp
+++ b/test_regress/t/t_dpi_lib_c.cpp
@@ -22,7 +22,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_lib__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(NC)
diff --git a/test_regress/t/t_dpi_open_c.cpp b/test_regress/t/t_dpi_open_c.cpp
index 01bd870fd..3adc602f3 100644
--- a/test_regress/t/t_dpi_open_c.cpp
+++ b/test_regress/t/t_dpi_open_c.cpp
@@ -22,7 +22,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_open__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(NC)
diff --git a/test_regress/t/t_dpi_open_elem_c.cpp b/test_regress/t/t_dpi_open_elem_c.cpp
index 2f4f24f51..35e59f74e 100644
--- a/test_regress/t/t_dpi_open_elem_c.cpp
+++ b/test_regress/t/t_dpi_open_elem_c.cpp
@@ -22,7 +22,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_open_elem__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(NC)
diff --git a/test_regress/t/t_dpi_open_oob_bad_c.cpp b/test_regress/t/t_dpi_open_oob_bad_c.cpp
index 4444a9654..24473edf6 100644
--- a/test_regress/t/t_dpi_open_oob_bad_c.cpp
+++ b/test_regress/t/t_dpi_open_oob_bad_c.cpp
@@ -22,7 +22,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_open_oob_bad__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #else
 # error "Unknown simulator for DPI test"
 #endif
diff --git a/test_regress/t/t_dpi_open_query.cpp b/test_regress/t/t_dpi_open_query.cpp
index 435562b86..b177b8e58 100644
--- a/test_regress/t/t_dpi_open_query.cpp
+++ b/test_regress/t/t_dpi_open_query.cpp
@@ -13,7 +13,7 @@
 
 // clang-format off
 #if defined(VERILATOR)  // Verilator
-# include "Vt_dpi_open_query__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)  // VCS
 # include "../vc_hdrs.h"
 #elif defined(NCSC)  // NC
diff --git a/test_regress/t/t_dpi_open_vecval_c.cpp b/test_regress/t/t_dpi_open_vecval_c.cpp
index e808239b2..fdd9424f2 100644
--- a/test_regress/t/t_dpi_open_vecval_c.cpp
+++ b/test_regress/t/t_dpi_open_vecval_c.cpp
@@ -22,7 +22,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_open_vecval__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(NC)
diff --git a/test_regress/t/t_dpi_openfirst_c.cpp b/test_regress/t/t_dpi_openfirst_c.cpp
index 97283a5b1..022745c30 100644
--- a/test_regress/t/t_dpi_openfirst_c.cpp
+++ b/test_regress/t/t_dpi_openfirst_c.cpp
@@ -22,7 +22,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_openfirst__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(NC)
diff --git a/test_regress/t/t_dpi_qw_c.cpp b/test_regress/t/t_dpi_qw_c.cpp
index 3bd07a405..61f881b6b 100644
--- a/test_regress/t/t_dpi_qw_c.cpp
+++ b/test_regress/t/t_dpi_qw_c.cpp
@@ -17,7 +17,7 @@
 //======================================================================
 
 #ifdef VERILATOR
-#include "Vt_dpi_qw__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #else
 extern "C" {
 extern void set_value(const svBitVecVal* v);
diff --git a/test_regress/t/t_dpi_result_type.cpp b/test_regress/t/t_dpi_result_type.cpp
index 2be445490..82a752491 100644
--- a/test_regress/t/t_dpi_result_type.cpp
+++ b/test_regress/t/t_dpi_result_type.cpp
@@ -17,7 +17,7 @@
 
 // clang-format off
 #if defined(VERILATOR)  // Verilator
-# include "Vt_dpi_result_type__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 typedef long long sv_longint_t;
 typedef unsigned long long sv_longint_unsigned_t;
 # define NO_SHORTREAL
diff --git a/test_regress/t/t_dpi_shortcircuit_c.cpp b/test_regress/t/t_dpi_shortcircuit_c.cpp
index 00607cd3b..1a7ca6c8a 100644
--- a/test_regress/t/t_dpi_shortcircuit_c.cpp
+++ b/test_regress/t/t_dpi_shortcircuit_c.cpp
@@ -18,13 +18,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# if defined(T_DPI_SHORTCIRCUIT)
-#  include "Vt_dpi_shortcircuit__Dpi.h"
-# elif defined(T_DPI_SHORTCIRCUIT2)
-#  include "Vt_dpi_shortcircuit2__Dpi.h"
-# else
-#  error "Unknown test"
-# endif
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(CADENCE)
diff --git a/test_regress/t/t_dpi_string_c.cpp b/test_regress/t/t_dpi_string_c.cpp
index fcf284699..03a893abc 100644
--- a/test_regress/t/t_dpi_string_c.cpp
+++ b/test_regress/t/t_dpi_string_c.cpp
@@ -18,7 +18,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_string__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(CADENCE)
diff --git a/test_regress/t/t_dpi_sys_c.cpp b/test_regress/t/t_dpi_sys_c.cpp
index 16553ca92..e67858095 100644
--- a/test_regress/t/t_dpi_sys_c.cpp
+++ b/test_regress/t/t_dpi_sys_c.cpp
@@ -17,7 +17,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_sys__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(CADENCE)
diff --git a/test_regress/t/t_dpi_threads_c.cpp b/test_regress/t/t_dpi_threads_c.cpp
index 09c61822c..2313cb75a 100644
--- a/test_regress/t/t_dpi_threads_c.cpp
+++ b/test_regress/t/t_dpi_threads_c.cpp
@@ -20,11 +20,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# ifdef T_DPI_THREADS_COLLIDE
-#  include "Vt_dpi_threads_collide__Dpi.h"
-# else
-#  include "Vt_dpi_threads__Dpi.h"
-# endif
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(CADENCE)
diff --git a/test_regress/t/t_dpi_vams.cpp b/test_regress/t/t_dpi_vams.cpp
index aacbaf9d6..32c4d17db 100644
--- a/test_regress/t/t_dpi_vams.cpp
+++ b/test_regress/t/t_dpi_vams.cpp
@@ -14,7 +14,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_dpi_vams__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(CADENCE)
diff --git a/test_regress/t/t_embed1_c.cpp b/test_regress/t/t_embed1_c.cpp
index d04d5b375..6004ef794 100644
--- a/test_regress/t/t_embed1_c.cpp
+++ b/test_regress/t/t_embed1_c.cpp
@@ -18,7 +18,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_embed1__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(CADENCE)
diff --git a/test_regress/t/t_flag_ldflags_c.cpp b/test_regress/t/t_flag_ldflags_c.cpp
index 276801399..32798e273 100644
--- a/test_regress/t/t_flag_ldflags_c.cpp
+++ b/test_regress/t/t_flag_ldflags_c.cpp
@@ -17,7 +17,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# include "Vt_flag_ldflags__Dpi.h"
+# include VM_PREFIX_INCLUDE_DPI
 #else
 # error "Unknown simulator for DPI test"
 #endif
diff --git a/test_regress/t/t_flag_lib_dpi.cpp b/test_regress/t/t_flag_lib_dpi.cpp
index ca49b5b9c..c8e8bd701 100644
--- a/test_regress/t/t_flag_lib_dpi.cpp
+++ b/test_regress/t/t_flag_lib_dpi.cpp
@@ -7,7 +7,7 @@
 //
 //*************************************************************************
 
-#include "Vt_flag_lib_dpi__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 #include <iostream>
diff --git a/test_regress/t/t_func_wide_out_c.cpp b/test_regress/t/t_func_wide_out_c.cpp
index 5f80aa1b3..e528066fe 100644
--- a/test_regress/t/t_func_wide_out_c.cpp
+++ b/test_regress/t/t_func_wide_out_c.cpp
@@ -18,13 +18,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# ifdef T_FUNC_WIDE_OUT
-#  include "Vt_func_wide_out__Dpi.h"
-# elif defined(T_FUNC_WIDE_OUT_NOINL)
-#  include "Vt_func_wide_out_noinl__Dpi.h"
-# else
-#  error "Unknown test"
-# endif
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #else
diff --git a/test_regress/t/t_nba_assign_on_rhs.py b/test_regress/t/t_nba_assign_on_rhs.py
index eafe7e6e5..0e433f0d6 100755
--- a/test_regress/t/t_nba_assign_on_rhs.py
+++ b/test_regress/t/t_nba_assign_on_rhs.py
@@ -15,4 +15,7 @@ test.compile()
 
 test.execute()
 
+# Hosts the no-DPI case for VM_PREFIX_INCLUDE_DPI; keep this design free of DPI and public
+test.file_grep_not(test.obj_dir + "/" + test.vm_prefix + ".mk", r'VM_PREFIX_INCLUDE_DPI')
+
 test.passes()
diff --git a/test_regress/t/t_opt_dead.cpp b/test_regress/t/t_opt_dead.cpp
index 3714dbfb7..9e7260ba2 100644
--- a/test_regress/t/t_opt_dead.cpp
+++ b/test_regress/t/t_opt_dead.cpp
@@ -5,6 +5,6 @@
 // SPDX-License-Identifier: CC0-1.0
 //*************************************************************************
 
-#include "Vt_opt_dead__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 
 void dpii_Keep() {}
diff --git a/test_regress/t/t_opt_lift_expr.cpp b/test_regress/t/t_opt_lift_expr.cpp
index 20e7905b7..d72efe6d5 100644
--- a/test_regress/t/t_opt_lift_expr.cpp
+++ b/test_regress/t/t_opt_lift_expr.cpp
@@ -9,7 +9,7 @@
 //
 //*************************************************************************
 
-#include "Vt_opt_lift_expr__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 svLogic impure_0() { return sv_0; }
diff --git a/test_regress/t/t_order_dpi_export_1.cpp b/test_regress/t/t_order_dpi_export_1.cpp
index 9f2fab1bf..9f514e0c2 100644
--- a/test_regress/t/t_order_dpi_export_1.cpp
+++ b/test_regress/t/t_order_dpi_export_1.cpp
@@ -10,7 +10,7 @@
 //*************************************************************************
 
 #include <Vt_order_dpi_export_1.h>
-#include <Vt_order_dpi_export_1__Dpi.h>
+#include VM_PREFIX_INCLUDE_DPI
 #include <svdpi.h>
 
 int main(int argc, char* argv[]) {
diff --git a/test_regress/t/t_order_dpi_export_2.cpp b/test_regress/t/t_order_dpi_export_2.cpp
index c50f725d3..77d24060e 100644
--- a/test_regress/t/t_order_dpi_export_2.cpp
+++ b/test_regress/t/t_order_dpi_export_2.cpp
@@ -10,7 +10,7 @@
 //*************************************************************************
 
 #include <Vt_order_dpi_export_2.h>
-#include <Vt_order_dpi_export_2__Dpi.h>
+#include VM_PREFIX_INCLUDE_DPI
 #include <svdpi.h>
 
 void toggle_other_clk(svBit val) { set_other_clk(val); }
diff --git a/test_regress/t/t_order_dpi_export_3.cpp b/test_regress/t/t_order_dpi_export_3.cpp
index 61ef97f38..d89494652 100644
--- a/test_regress/t/t_order_dpi_export_3.cpp
+++ b/test_regress/t/t_order_dpi_export_3.cpp
@@ -10,7 +10,7 @@
 //*************************************************************************
 
 #include <Vt_order_dpi_export_3.h>
-#include <Vt_order_dpi_export_3__Dpi.h>
+#include VM_PREFIX_INCLUDE_DPI
 #include <svdpi.h>
 
 void toggle_other_clk(svBit val) { set_other_clk(val); }
diff --git a/test_regress/t/t_order_dpi_export_4.cpp b/test_regress/t/t_order_dpi_export_4.cpp
index 5f0e16dbe..7967fe493 100644
--- a/test_regress/t/t_order_dpi_export_4.cpp
+++ b/test_regress/t/t_order_dpi_export_4.cpp
@@ -10,7 +10,7 @@
 //*************************************************************************
 
 #include <Vt_order_dpi_export_4.h>
-#include <Vt_order_dpi_export_4__Dpi.h>
+#include VM_PREFIX_INCLUDE_DPI
 #include <svdpi.h>
 
 void toggle_other_clk(svBit val) { set_other_clk(val); }
diff --git a/test_regress/t/t_order_dpi_export_5.cpp b/test_regress/t/t_order_dpi_export_5.cpp
index 2977049f5..a7715b672 100644
--- a/test_regress/t/t_order_dpi_export_5.cpp
+++ b/test_regress/t/t_order_dpi_export_5.cpp
@@ -10,7 +10,7 @@
 //*************************************************************************
 
 #include <Vt_order_dpi_export_5.h>
-#include <Vt_order_dpi_export_5__Dpi.h>
+#include VM_PREFIX_INCLUDE_DPI
 #include <svdpi.h>
 
 int main(int argc, char* argv[]) {
diff --git a/test_regress/t/t_order_dpi_export_6.cpp b/test_regress/t/t_order_dpi_export_6.cpp
index 8e54d032c..3af35034e 100644
--- a/test_regress/t/t_order_dpi_export_6.cpp
+++ b/test_regress/t/t_order_dpi_export_6.cpp
@@ -10,7 +10,7 @@
 //*************************************************************************
 
 #include <Vt_order_dpi_export_6.h>
-#include <Vt_order_dpi_export_6__Dpi.h>
+#include VM_PREFIX_INCLUDE_DPI
 #include <svdpi.h>
 
 void toggle_other_clk(svBit val) { set_other_clk(val); }
diff --git a/test_regress/t/t_order_dpi_export_7.cpp b/test_regress/t/t_order_dpi_export_7.cpp
index 73043298b..df49048e7 100644
--- a/test_regress/t/t_order_dpi_export_7.cpp
+++ b/test_regress/t/t_order_dpi_export_7.cpp
@@ -10,7 +10,7 @@
 //*************************************************************************
 
 #include <Vt_order_dpi_export_7.h>
-#include <Vt_order_dpi_export_7__Dpi.h>
+#include VM_PREFIX_INCLUDE_DPI
 #include <svdpi.h>
 
 int main(int argc, char* argv[]) {
diff --git a/test_regress/t/t_order_dpi_export_8.cpp b/test_regress/t/t_order_dpi_export_8.cpp
index 28626f656..dc36b5838 100644
--- a/test_regress/t/t_order_dpi_export_8.cpp
+++ b/test_regress/t/t_order_dpi_export_8.cpp
@@ -9,7 +9,7 @@
 //
 //*************************************************************************
 
-#include <Vt_order_dpi_export_8__Dpi.h>
+#include VM_PREFIX_INCLUDE_DPI
 #include <svdpi.h>
 
 void call_set_x(svBit val) { set_x(val); }
diff --git a/test_regress/t/t_protect_ids_c.cpp b/test_regress/t/t_protect_ids_c.cpp
index 9a52816b9..c0c6e5304 100644
--- a/test_regress/t/t_protect_ids_c.cpp
+++ b/test_regress/t/t_protect_ids_c.cpp
@@ -18,11 +18,7 @@
 
 // clang-format off
 #if defined(VERILATOR)
-# ifdef T_PROTECT_IDS_KEY
-#  include "Vt_protect_ids_key__Dpi.h"
-# else
-#  include "Vt_protect_ids__Dpi.h"
-# endif
+# include VM_PREFIX_INCLUDE_DPI
 #elif defined(VCS)
 # include "../vc_hdrs.h"
 #elif defined(CADENCE)
diff --git a/test_regress/t/t_vm_prefix_include_cmake.py b/test_regress/t/t_vm_prefix_include_cmake.py
new file mode 100755
index 000000000..7952af20f
--- /dev/null
+++ b/test_regress/t/t_vm_prefix_include_cmake.py
@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of either the GNU Lesser General Public License Version 3
+# or the Perl Artistic License Version 2.0.
+# SPDX-FileCopyrightText: 2026 Wilson Snyder
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+import vltest_bootstrap
+
+test.scenarios('vlt')
+test.top_filename = "t/t_dpi_decl.v"
+
+test.compile(v_flags2=["t/t_dpi_decl.cpp"], verilator_make_gmake=False, verilator_make_cmake=True)
+
+test.execute()
+
+test.passes()
diff --git a/test_regress/t/t_vpi_const_type.cpp b/test_regress/t/t_vpi_const_type.cpp
index fb3109432..60d12ae32 100644
--- a/test_regress/t/t_vpi_const_type.cpp
+++ b/test_regress/t/t_vpi_const_type.cpp
@@ -22,7 +22,7 @@
 #include "verilated_vpi.h"
 
 #include "Vt_vpi_const_type.h"
-#include "Vt_vpi_const_type__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 #endif
diff --git a/test_regress/t/t_vpi_escape.cpp b/test_regress/t/t_vpi_escape.cpp
index 929c30109..bd40dfc5d 100644
--- a/test_regress/t/t_vpi_escape.cpp
+++ b/test_regress/t/t_vpi_escape.cpp
@@ -20,7 +20,7 @@
 #include "verilated_vpi.h"
 
 #include "Vt_vpi_escape.h"
-#include "Vt_vpi_escape__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 #endif
diff --git a/test_regress/t/t_vpi_get.cpp b/test_regress/t/t_vpi_get.cpp
index 93e957cea..0671e17e1 100644
--- a/test_regress/t/t_vpi_get.cpp
+++ b/test_regress/t/t_vpi_get.cpp
@@ -22,7 +22,7 @@
 #include "verilated_vpi.h"
 
 #include "Vt_vpi_get.h"
-#include "Vt_vpi_get__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 #endif
diff --git a/test_regress/t/t_vpi_memory.cpp b/test_regress/t/t_vpi_memory.cpp
index 4518a2ac4..07aa92f68 100644
--- a/test_regress/t/t_vpi_memory.cpp
+++ b/test_regress/t/t_vpi_memory.cpp
@@ -22,7 +22,7 @@
 #include "verilated_vpi.h"
 
 #include "Vt_vpi_memory.h"
-#include "Vt_vpi_memory__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 #endif
diff --git a/test_regress/t/t_vpi_module.cpp b/test_regress/t/t_vpi_module.cpp
index 169088f84..7ecf8aada 100644
--- a/test_regress/t/t_vpi_module.cpp
+++ b/test_regress/t/t_vpi_module.cpp
@@ -22,7 +22,7 @@
 #include "verilated_vpi.h"
 
 #include "Vt_vpi_module.h"
-#include "Vt_vpi_module__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 #endif
diff --git a/test_regress/t/t_vpi_module_empty.cpp b/test_regress/t/t_vpi_module_empty.cpp
index 652a6a5a0..71692babc 100644
--- a/test_regress/t/t_vpi_module_empty.cpp
+++ b/test_regress/t/t_vpi_module_empty.cpp
@@ -22,7 +22,7 @@
 #include "verilated_vpi.h"
 
 #include "Vt_vpi_module_empty.h"
-#include "Vt_vpi_module_empty__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 #endif
diff --git a/test_regress/t/t_vpi_multidim.cpp b/test_regress/t/t_vpi_multidim.cpp
index 60250f5f7..0e8fb36d5 100644
--- a/test_regress/t/t_vpi_multidim.cpp
+++ b/test_regress/t/t_vpi_multidim.cpp
@@ -22,7 +22,7 @@
 #include "verilated_vpi.h"
 
 #include "Vt_vpi_multidim.h"
-#include "Vt_vpi_multidim__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 #endif
diff --git a/test_regress/t/t_vpi_package.cpp b/test_regress/t/t_vpi_package.cpp
index 409d78f6a..244a347bf 100644
--- a/test_regress/t/t_vpi_package.cpp
+++ b/test_regress/t/t_vpi_package.cpp
@@ -22,7 +22,7 @@
 #include "verilated_vpi.h"
 
 #include "Vt_vpi_package.h"
-#include "Vt_vpi_package__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 #endif
diff --git a/test_regress/t/t_vpi_param.cpp b/test_regress/t/t_vpi_param.cpp
index 29cd0511f..345d34534 100644
--- a/test_regress/t/t_vpi_param.cpp
+++ b/test_regress/t/t_vpi_param.cpp
@@ -25,7 +25,7 @@
 
 #ifdef T_VPI_PARAM
 #include "Vt_vpi_param.h"
-#include "Vt_vpi_param__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #elif defined(T_VPI_PUBLIC_PARAMS)
 #include "Vt_vpi_public_params.h"
 #else
diff --git a/test_regress/t/t_vpi_public_depth.cpp b/test_regress/t/t_vpi_public_depth.cpp
index 61f9c4dea..bda78c499 100644
--- a/test_regress/t/t_vpi_public_depth.cpp
+++ b/test_regress/t/t_vpi_public_depth.cpp
@@ -22,15 +22,7 @@
 #include "verilated_vpi.h"
 
 #include VM_PREFIX_INCLUDE
-#ifdef T_VPI_PUBLIC_DEPTH
-#include "Vt_vpi_public_depth__Dpi.h"
-#elif defined(T_VPI_PUBLIC_DEPTH_OFF)
-#include "Vt_vpi_public_depth_off__Dpi.h"
-#elif defined(T_VPI_PUBLIC_OFF)
-#include "Vt_vpi_public_off__Dpi.h"
-#else
-#error "Bad test"
-#endif
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 #endif
diff --git a/test_regress/t/t_vpi_release_dup_bad_c.cpp b/test_regress/t/t_vpi_release_dup_bad_c.cpp
index 62ea5781b..68aca8bda 100644
--- a/test_regress/t/t_vpi_release_dup_bad_c.cpp
+++ b/test_regress/t/t_vpi_release_dup_bad_c.cpp
@@ -15,7 +15,7 @@
 #include <cstdio>
 //#include "verilated.h"
 
-#include "Vt_vpi_release_dup_bad__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 
 //======================================================================
 
diff --git a/test_regress/t/t_vpi_time_cb.cpp b/test_regress/t/t_vpi_time_cb.cpp
index 1aa0da70c..901cc65c4 100644
--- a/test_regress/t/t_vpi_time_cb.cpp
+++ b/test_regress/t/t_vpi_time_cb.cpp
@@ -14,7 +14,7 @@
 #include "verilated_vpi.h"
 
 #include "Vt_vpi_time_cb.h"
-#include "Vt_vpi_time_cb__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 #include <iostream>
diff --git a/test_regress/t/t_vpi_unimpl.cpp b/test_regress/t/t_vpi_unimpl.cpp
index 359089492..ae6fd91fb 100644
--- a/test_regress/t/t_vpi_unimpl.cpp
+++ b/test_regress/t/t_vpi_unimpl.cpp
@@ -13,7 +13,7 @@
 #include "verilated_vcd_c.h"
 
 #include "Vt_vpi_unimpl.h"
-#include "Vt_vpi_unimpl__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 // No verilated_vpi.h, make sure can link without it
 
diff --git a/test_regress/t/t_vpi_var.cpp b/test_regress/t/t_vpi_var.cpp
index 6fa71bfda..3529257e5 100644
--- a/test_regress/t/t_vpi_var.cpp
+++ b/test_regress/t/t_vpi_var.cpp
@@ -20,19 +20,8 @@
 #include "verilated_vcd_c.h"
 #include "verilated_vpi.h"
 
-#ifdef T_VPI_VAR2
-#include "Vt_vpi_var2.h"
-#include "Vt_vpi_var2__Dpi.h"
-#elif defined(T_VPI_VAR3)
-#include "Vt_vpi_var3.h"
-#include "Vt_vpi_var3__Dpi.h"
-#elif defined(T_VPI_FORCEABLE_VAR)
-#include "Vt_vpi_forceable_var.h"
-#include "Vt_vpi_forceable_var__Dpi.h"
-#else
-#include "Vt_vpi_var.h"
-#include "Vt_vpi_var__Dpi.h"
-#endif
+#include VM_PREFIX_INCLUDE
+#include VM_PREFIX_INCLUDE_DPI
 
 #include "svdpi.h"
 
diff --git a/test_regress/t/t_vpi_zero_time_cb.cpp b/test_regress/t/t_vpi_zero_time_cb.cpp
index 82b742ccc..1bde145af 100644
--- a/test_regress/t/t_vpi_zero_time_cb.cpp
+++ b/test_regress/t/t_vpi_zero_time_cb.cpp
@@ -20,7 +20,7 @@
 #include "verilated_vpi.h"
 
 #include "Vt_vpi_zero_time_cb.h"
-#include "Vt_vpi_zero_time_cb__Dpi.h"
+#include VM_PREFIX_INCLUDE_DPI
 #include "svdpi.h"
 
 #include <dlfcn.h>
diff --git a/test_regress/t/trace_lib_as_top_common.py b/test_regress/t/trace_lib_as_top_common.py
index 97508b877..58661339f 100644
--- a/test_regress/t/trace_lib_as_top_common.py
+++ b/test_regress/t/trace_lib_as_top_common.py
@@ -31,8 +31,7 @@ def run(test, *, verilator_flags2=()):
     ]
     flags.extend(verilator_flags2)
 
-    cflags = (f'-DVM_PREFIX={test.vm_prefix} '
-              f"-DVM_PREFIX_INCLUDE='<{test.vm_prefix}.h>' ")
+    cflags = f'-DVM_PREFIX={test.vm_prefix} '
 
     # Compile and run without lib-create
     test.compile(verilator_flags2=[test.pli_filename] + flags +
diff --git a/verilator-config.cmake.in b/verilator-config.cmake.in
index 33f09a03a..a12b7aa02 100644
--- a/verilator-config.cmake.in
+++ b/verilator-config.cmake.in
@@ -468,6 +468,7 @@ function(verilate TARGET)
         json_get_list(JOPTIONS_LDFLAGS "${MANIFEST}" options ldflags)
         json_get_bool(JOPTIONS_SYSTEM_C "${MANIFEST}" options system_c)
         json_get_bool(JOPTIONS_COVERAGE "${MANIFEST}" options coverage)
+        json_get_bool(JOPTIONS_DPI "${MANIFEST}" options dpi)
         json_get_bool(JOPTIONS_USE_TIMING "${MANIFEST}" options use_timing)
         json_get_int(JOPTIONS_THREADS "${MANIFEST}" options threads)
         json_get_bool(JOPTIONS_TRACE_FST "${MANIFEST}" options trace_fst)
@@ -505,6 +506,8 @@ function(verilate TARGET)
             "set(${VERILATE_PREFIX}_SC ${JOPTIONS_SYSTEM_C})\n"
             "# Coverage output mode?  0/1 (from --coverage)\n"
             "set(${VERILATE_PREFIX}_COVERAGE ${JOPTIONS_COVERAGE})\n"
+            "# DPI generated?  0/1\n"
+            "set(${VERILATE_PREFIX}_DPI ${JOPTIONS_DPI})\n"
             "# Timing mode?  0/1\n"
             "set(${VERILATE_PREFIX}_TIMING ${JOPTIONS_USE_TIMING})\n"
             "# Threaded output mode?  1/N threads (from --threads)\n"
@@ -741,6 +744,23 @@ function(verilate TARGET)
             VM_TRACE_FST=$<BOOL:$<TARGET_PROPERTY:VERILATOR_TRACE_FST>>
             VM_TRACE_SAIF=$<BOOL:$<TARGET_PROPERTY:VERILATOR_TRACE_SAIF>>
     )
+    # verilate() may be called repeatedly on one target, each call with its own
+    # prefix, so only the first model defines these; redefining them would warn
+    # (error under -Werror) on every translation unit of the target
+    get_target_property(VERILATE_DEFINITIONS ${TARGET} COMPILE_DEFINITIONS)
+    if(NOT VERILATE_DEFINITIONS MATCHES "(^|;)VM_PREFIX_INCLUDE=")
+        target_compile_definitions(
+            ${TARGET}
+            PRIVATE "VM_PREFIX_INCLUDE=<${VERILATE_PREFIX}.h>"
+        )
+        if(${VERILATE_PREFIX}_DPI)
+            # Left undefined when the design has no DPI, so misuse fails at compile time
+            target_compile_definitions(
+                ${TARGET}
+                PRIVATE "VM_PREFIX_INCLUDE_DPI=<${VERILATE_PREFIX}__Dpi.h>"
+            )
+        endif()
+    endif()
 
     target_link_libraries(${TARGET} PUBLIC ${${VERILATE_PREFIX}_USER_LDLIBS})