diff --git a/common/conf_post.h b/common/conf_post.h
index f79070d..b9a48a5 100644
--- a/common/conf_post.h
+++ b/common/conf_post.h
@@ -76,9 +76,6 @@ typedef int ssize_t;
 #if defined(REAL_GCC) && defined(HAVE_FEATURES_H)
 // Older gcc versions pretended to supply std::regex, but the resulting programs mostly crashed.
 #include <features.h>
-#if ! __GNUC_PREREQ(6,0)
-#define NO_STD_REGEX 1
-#endif
 #endif
 
 #endif /* INCLUDED */