diff --git a/test_regress/t/TestVpiMain.cpp b/test_regress/t/TestVpiMain.cpp
index e51323177..b72127d15 100644
--- a/test_regress/t/TestVpiMain.cpp
+++ b/test_regress/t/TestVpiMain.cpp
@@ -21,6 +21,10 @@
 #include <cstdint>
 #include <memory>
 
+extern "C" {
+#include <libgen.h>
+}
+
 #ifndef VM_TRACE_FST
 // emulate new verilator behavior for legacy versions
 #define VM_TRACE_FST 0
diff --git a/test_regress/t/t_time_vpi_c.cpp b/test_regress/t/t_time_vpi_c.cpp
index 86ab6a5ef..8063f5bbf 100644
--- a/test_regress/t/t_time_vpi_c.cpp
+++ b/test_regress/t/t_time_vpi_c.cpp
@@ -15,6 +15,10 @@
 #include <cstdio>
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestCheck.h"
 #include "TestVpi.h"
diff --git a/test_regress/t/t_vpi_cb_iter.cpp b/test_regress/t/t_vpi_cb_iter.cpp
index d98fe968c..b5af77a6f 100644
--- a/test_regress/t/t_vpi_cb_iter.cpp
+++ b/test_regress/t/t_vpi_cb_iter.cpp
@@ -22,6 +22,10 @@
 #include <iostream>
 #include <vector>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestCheck.h"
 #include "TestSimulator.h"
diff --git a/test_regress/t/t_vpi_const_type.cpp b/test_regress/t/t_vpi_const_type.cpp
index 5efd97175..04812fb54 100644
--- a/test_regress/t/t_vpi_const_type.cpp
+++ b/test_regress/t/t_vpi_const_type.cpp
@@ -31,6 +31,10 @@
 #include <cstring>
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestSimulator.h"
 #include "TestVpi.h"
diff --git a/test_regress/t/t_vpi_dump.cpp b/test_regress/t/t_vpi_dump.cpp
index cf2147e54..b3c7a7c3c 100644
--- a/test_regress/t/t_vpi_dump.cpp
+++ b/test_regress/t/t_vpi_dump.cpp
@@ -14,6 +14,10 @@
 
 #include <cstdio>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestCheck.h"
 #include "TestSimulator.h"
diff --git a/test_regress/t/t_vpi_escape.cpp b/test_regress/t/t_vpi_escape.cpp
index 85acca39b..3018a20ea 100644
--- a/test_regress/t/t_vpi_escape.cpp
+++ b/test_regress/t/t_vpi_escape.cpp
@@ -27,6 +27,10 @@
 
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestCheck.h"
 #include "TestSimulator.h"
diff --git a/test_regress/t/t_vpi_get.cpp b/test_regress/t/t_vpi_get.cpp
index 7a9e5711f..a3a802514 100644
--- a/test_regress/t/t_vpi_get.cpp
+++ b/test_regress/t/t_vpi_get.cpp
@@ -31,6 +31,10 @@
 #include <cstring>
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestSimulator.h"
 #include "TestVpi.h"
diff --git a/test_regress/t/t_vpi_get_value_array.cpp b/test_regress/t/t_vpi_get_value_array.cpp
index 621d1ac62..c1f3bcc5e 100644
--- a/test_regress/t/t_vpi_get_value_array.cpp
+++ b/test_regress/t/t_vpi_get_value_array.cpp
@@ -18,6 +18,10 @@
 
 #endif
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestSimulator.h"
 #include "TestVpi.h"
diff --git a/test_regress/t/t_vpi_memory.cpp b/test_regress/t/t_vpi_memory.cpp
index 857ee2d90..c0268c4ab 100644
--- a/test_regress/t/t_vpi_memory.cpp
+++ b/test_regress/t/t_vpi_memory.cpp
@@ -31,6 +31,10 @@
 #include <cstring>
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestCheck.h"
 #include "TestSimulator.h"
diff --git a/test_regress/t/t_vpi_module.cpp b/test_regress/t/t_vpi_module.cpp
index a0a3c030f..886487fa7 100644
--- a/test_regress/t/t_vpi_module.cpp
+++ b/test_regress/t/t_vpi_module.cpp
@@ -31,6 +31,10 @@
 #include <cstring>
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestSimulator.h"
 #include "TestVpi.h"
diff --git a/test_regress/t/t_vpi_module_empty.cpp b/test_regress/t/t_vpi_module_empty.cpp
index f08ebb27d..dd79c521a 100644
--- a/test_regress/t/t_vpi_module_empty.cpp
+++ b/test_regress/t/t_vpi_module_empty.cpp
@@ -31,6 +31,10 @@
 #include <cstring>
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestSimulator.h"
 #include "TestVpi.h"
diff --git a/test_regress/t/t_vpi_multidim.cpp b/test_regress/t/t_vpi_multidim.cpp
index 8a2f155a0..79fbb3bf3 100644
--- a/test_regress/t/t_vpi_multidim.cpp
+++ b/test_regress/t/t_vpi_multidim.cpp
@@ -28,12 +28,17 @@
 #endif
 
 #include <cassert>
+#include <cinttypes>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
 #include <iostream>
 #include <random>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestCheck.h"
 #include "TestSimulator.h"
diff --git a/test_regress/t/t_vpi_onetime_cbs.cpp b/test_regress/t/t_vpi_onetime_cbs.cpp
index 4adf77969..c9945ab9c 100644
--- a/test_regress/t/t_vpi_onetime_cbs.cpp
+++ b/test_regress/t/t_vpi_onetime_cbs.cpp
@@ -27,6 +27,11 @@
 
 #endif
 
+extern "C" {
+#include <libgen.h>
+}
+
+// These require the above. Comment prevents clang-format moving them
 #include "TestSimulator.h"
 #include "TestVpi.h"
 
diff --git a/test_regress/t/t_vpi_package.cpp b/test_regress/t/t_vpi_package.cpp
index c36b28f1e..93360131f 100644
--- a/test_regress/t/t_vpi_package.cpp
+++ b/test_regress/t/t_vpi_package.cpp
@@ -31,6 +31,10 @@
 #include <cstring>
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestSimulator.h"
 #include "TestVpi.h"
diff --git a/test_regress/t/t_vpi_param.cpp b/test_regress/t/t_vpi_param.cpp
index d5700b10a..9ce832fbd 100644
--- a/test_regress/t/t_vpi_param.cpp
+++ b/test_regress/t/t_vpi_param.cpp
@@ -38,6 +38,10 @@
 #include <cstring>
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestSimulator.h"
 #include "TestVpi.h"
diff --git a/test_regress/t/t_vpi_public_depth.cpp b/test_regress/t/t_vpi_public_depth.cpp
index e1bf6e2a6..4d9b9971b 100644
--- a/test_regress/t/t_vpi_public_depth.cpp
+++ b/test_regress/t/t_vpi_public_depth.cpp
@@ -39,6 +39,10 @@
 #include <cstring>
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestSimulator.h"
 #include "TestVpi.h"
diff --git a/test_regress/t/t_vpi_put_value_array.cpp b/test_regress/t/t_vpi_put_value_array.cpp
index b8f8c65a7..6e6294267 100644
--- a/test_regress/t/t_vpi_put_value_array.cpp
+++ b/test_regress/t/t_vpi_put_value_array.cpp
@@ -18,6 +18,10 @@
 
 #endif
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestSimulator.h"
 #include "TestVpi.h"
diff --git a/test_regress/t/t_vpi_repetitive_cbs.cpp b/test_regress/t/t_vpi_repetitive_cbs.cpp
index 1ed4e48f6..107a77629 100644
--- a/test_regress/t/t_vpi_repetitive_cbs.cpp
+++ b/test_regress/t/t_vpi_repetitive_cbs.cpp
@@ -29,6 +29,10 @@
 #include <iostream>
 #include <vector>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestSimulator.h"
 #include "TestVpi.h"
diff --git a/test_regress/t/t_vpi_time_cb_c.cpp b/test_regress/t/t_vpi_time_cb_c.cpp
index 4f69d232c..00e50b5fe 100644
--- a/test_regress/t/t_vpi_time_cb_c.cpp
+++ b/test_regress/t/t_vpi_time_cb_c.cpp
@@ -16,6 +16,10 @@
 #include <cstring>
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestCheck.h"
 #include "TestSimulator.h"
diff --git a/test_regress/t/t_vpi_unimpl.cpp b/test_regress/t/t_vpi_unimpl.cpp
index 732b30d53..fa6f5291f 100644
--- a/test_regress/t/t_vpi_unimpl.cpp
+++ b/test_regress/t/t_vpi_unimpl.cpp
@@ -19,6 +19,10 @@
 
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestVpi.h"
 
diff --git a/test_regress/t/t_vpi_var.cpp b/test_regress/t/t_vpi_var.cpp
index 91b15b185..020961907 100644
--- a/test_regress/t/t_vpi_var.cpp
+++ b/test_regress/t/t_vpi_var.cpp
@@ -44,6 +44,10 @@
 #include <cstring>
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestCheck.h"
 #include "TestSimulator.h"
diff --git a/test_regress/t/t_vpi_zero_time_cb.cpp b/test_regress/t/t_vpi_zero_time_cb.cpp
index e19bd7f38..fe2d183fa 100644
--- a/test_regress/t/t_vpi_zero_time_cb.cpp
+++ b/test_regress/t/t_vpi_zero_time_cb.cpp
@@ -32,6 +32,10 @@
 #include <cstring>
 #include <iostream>
 
+extern "C" {
+#include <libgen.h>
+}
+
 // These require the above. Comment prevents clang-format moving them
 #include "TestCheck.h"
 #include "TestSimulator.h"