1 files changed, 10 insertions, 0 deletions
diff --git a/errno.h b/errno.h
index 0f4353e..85d862e 100644
--- a/errno.h
+++ b/errno.h
@@ -48,6 +48,14 @@ SOFTWARE.
 #	define _POSIX_SOURCE
 #endif
 
+#if !defined __STDC_VERSION__ || __STDC_VERSION__ < 19901L
+#	if (defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 200112L)
+#		error POSIX.1-2001 and later require a C99 compiler
+#	elif (defined _XOPEN_SOURCE && _XOPEN_SOURCE >= 600)
+#		error XOPEN Issue 6 and later require a C99 compiler
+#	endif
+#endif
+
 /* ./src/errno/EDOM.c */
 #define EDOM                                                                 (1)
 /* ./src/errno/ERANGE.c */
@@ -238,3 +246,5 @@ int *__errno(void);
 
 
 #endif
+
+#include <ungol/errno.h>