diff --git a/debug/tst-chk1.c b/debug/tst-chk1.c
index 0ec8ab07d9..7f0186e706 100644
--- a/debug/tst-chk1.c
+++ b/debug/tst-chk1.c
@@ -33,6 +33,12 @@
 #include <sys/socket.h>
 #include <sys/un.h>
 
+__BEGIN_DECLS
+/* The <stdio.h> header does not include the declaration for gets
+   anymore when compiling with _GNU_SOURCE.  Provide a copy here.  */
+extern char *gets (char *__s);
+__END_DECLS
+
 #define obstack_chunk_alloc malloc
 #define obstack_chunk_free free