diff --git a/makefile b/makefile
index cc39d0e5..853a7086 100644
--- a/makefile
+++ b/makefile
@@ -504,16 +504,6 @@ ifeq ($(WIN32),)  #*nix Environments (&& cygwin)
       endif
     endif
   endif
-  ifeq (,$(findstring DHAVE_PCREPOSIX_H,$(OS_CCDEFS)))
-    # If libpcreposix isn't available, fall back to the local regex.h 
-    # Presume that the local regex support is available in the C runtime 
-    # without a specific reference to a library.  This may not be true on
-    # some platforms.
-    ifneq (,$(call find_include,regex))
-      OS_CCDEFS += -DHAVE_REGEX_H
-      $(info using regex: $(call find_include,regex))
-    endif
-  endif
   # Find available ncurses library.
   ifneq (,$(call find_include,ncurses))
     ifneq (,$(call find_lib,ncurses))
diff --git a/sim_defs.h b/sim_defs.h
index e400c6e1..b793ae8e 100644
--- a/sim_defs.h
+++ b/sim_defs.h
@@ -150,9 +150,6 @@ extern int sim_vax_snprintf(char *buf, size_t buf_size, const char *fmt, ...);
 #include <pcreposix.h>
 #include <pcre.h>
 #define USE_REGEX 1
-#elif defined(HAVE_REGEX_H)
-#include <regex.h>
-#define USE_REGEX 1
 #endif
 
 #ifdef  __cplusplus