diff --git a/bin/verilator b/bin/verilator
index 3855f1aa1..50d299a70 100755
--- a/bin/verilator
+++ b/bin/verilator
@@ -1638,8 +1638,8 @@ will toggle forever and thus the executable will give the didn't converge
 error to prevent an infinite loop.
 
 To debug this, run Verilator with --profile-cfuncs.  Run make on the
-generated files with "CPPFLAGS_ADD=-DVL_DEBUG". Then call
-Verilated::debug(1) in your main.cpp.
+generated files with "OPT=-DVL_DEBUG". Then call Verilated::debug(1) in
+your main.cpp.
 
 This will cause each change in a variable to print a message.  Near the
 bottom you'll see the code and variable that causes the problem.  For the
diff --git a/include/verilated.mk.in b/include/verilated.mk.in
index 918e89a3a..83c846354 100644
--- a/include/verilated.mk.in
+++ b/include/verilated.mk.in
@@ -84,8 +84,8 @@ endif
 ##### SystemPerl builds
 
 ifeq ($(VM_SP),1)
-  CPPFLAGS += -I$(SYSTEMPERL) -I$(SYSTEMPERL)/src -DSYSTEMPERL
-  VPATH    +=   $(SYSTEMPERL)   $(SYSTEMPERL)/src
+  CPPFLAGS += -I$(SYSTEMPERL)/src -DSYSTEMPERL
+  VPATH    +=   $(SYSTEMPERL)/src
 
   VK_CLASSES_SP = $(addsuffix .sp, $(VM_CLASSES))
 
@@ -104,8 +104,8 @@ endif
 ifeq ($(VM_PCLI),1)
   LIBS   += -lm -lstdc++
  ifeq ($(VM_TRACE),1)
-  CPPFLAGS += -I$(SYSTEMPERL) -I$(SYSTEMPERL)/src
-  VPATH    +=   $(SYSTEMPERL)   $(SYSTEMPERL)/src
+  CPPFLAGS += -I$(SYSTEMPERL)/src
+  VPATH    +=   $(SYSTEMPERL)/src
  endif
 endif
 
diff --git a/include/verilatedos.h b/include/verilatedos.h
index 9fa98e848..1fd944ad2 100644
--- a/include/verilatedos.h
+++ b/include/verilatedos.h
@@ -39,6 +39,8 @@
 # define VL_ATTR_UNUSED __attribute__ ((unused))
 # define VL_LIKELY(x)	__builtin_expect(!!(x), 1)
 # define VL_UNLIKELY(x)	__builtin_expect(!!(x), 0)
+# define VL_PREFETCH_RD(p) __builtin_prefetch((p),0)
+# define VL_PREFETCH_RW(p) __builtin_prefetch((p),1)
 #else
 # define VL_ATTR_PRINTF(fmtArgNum)	///< Function with printf format checking
 # define VL_ATTR_ALIGNED(alignment)	///< Align structure to specified byte alignment
@@ -46,6 +48,8 @@
 # define VL_ATTR_UNUSED			///< Function that may be never used
 # define VL_LIKELY(x)	(!!(x))		///< Boolean expression more often true then false
 # define VL_UNLIKELY(x)	(!!(x))		///< Boolean expression more often false then true
+# define VL_PREFETCH_RD(p)		///< Prefetch data with read intent
+# define VL_PREFETCH_RW(p)		///< Prefetch data with read/write intent
 #endif
 
 #ifdef VL_THREADED