diff --git a/gcc/config.in b/gcc/config.in
index 0b14498ec93..c804a2b682e 100644
--- a/gcc/config.in
+++ b/gcc/config.in
@@ -94,6 +94,9 @@
 /* Whether strsignal must be declared even if <string.h> is included.  */
 #undef NEED_DECLARATION_STRSIGNAL
 
+/* Whether strstr must be declared even if <string.h> is included.  */
+#undef NEED_DECLARATION_STRSTR
+
 /* Whether getcwd must be declared even if <unistd.h> is included.  */
 #undef NEED_DECLARATION_GETCWD