diff --git a/src/core/include/gnuregex.h b/src/core/include/gnuregex.h
index 26faa6ea3..ce3202b4e 100644
--- a/src/core/include/gnuregex.h
+++ b/src/core/include/gnuregex.h
@@ -466,8 +466,8 @@ _RE_ARGS ((struct re_pattern_buffer *buffer, struct re_registers *regs,
            unsigned num_regs, regoff_t *starts, regoff_t *ends));
 
 /* 4.2 bsd compatibility.  */
-extern char *re_comp _RE_ARGS ((const char *));
-extern int re_exec _RE_ARGS ((const char *));
+extern "C" char *re_comp _RE_ARGS ((const char *));
+extern "C" int re_exec _RE_ARGS ((const char *));
 
 /* POSIX compatibility.  */
 extern int regcomp _RE_ARGS ((regex_t *preg, const char *pattern, int cflags));