diff --git a/ChangeLog b/ChangeLog
index 0d1a1ea9e7..3c90affd38 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 Sun May 26 15:15:08 1996  Roland McGrath  <roland@delasyd.gnu.ai.mit.edu>
 
+	* features.h [_GNU_SOURCE || _BSD_SOURCE || _SVID_SOURCE ||
+	_POSIX_SOURCE || _POSIX_C_SOURCE]: #undef __STRICT_ANSI__.
+
 	* time/Makefile (tzcompile): Add missing backslash.
 
 	* stdlib/ldiv.c: Deansideclized.
diff --git a/features.h b/features.h
index 4b50bea75a..ccf3a3793e 100644
--- a/features.h
+++ b/features.h
@@ -79,6 +79,13 @@ Cambridge, MA 02139, USA.  */
 #define	__FAVOR_BSD	1
 #endif
 
+/* Explicit features turn off -ansi.  */
+#if (defined (_GNU_SOURCE) || \
+     defined (_BSD_SOURCE) || defined (_SVID_SOURCE) || \
+     defined (_POSIX_SOURCE) || defined (_POSIX_C_SOURCE))
+#undef __STRICT_ANSI__
+#endif
+
 /* If _GNU_SOURCE was defined by the user, turn on all the other features.  */
 #ifdef _GNU_SOURCE
 /* If the user specifies some of the following without _GNU_SOURCE,