diff --git a/posix/fnmatch_loop.c b/posix/fnmatch_loop.c
index 72c5d8f..f46c9df 100644
--- a/posix/fnmatch_loop.c
+++ b/posix/fnmatch_loop.c
@@ -1036,7 +1036,12 @@ END (const CHAR *pattern)
       }
     else if ((*p == L('?') || *p == L('*') || *p == L('+') || *p == L('@')
 	      || *p == L('!')) && p[1] == L('('))
-      p = END (p + 1);
+      {
+	p = END (p + 1);
+	if (*p == L('\0'))
+	  /* This is an invalid pattern.  */
+	  return pattern;
+      }
     else if (*p == L(')'))
       break;
 
diff --git a/posix/tst-fnmatch3.c b/posix/tst-fnmatch3.c
index 75bc00a..7822a35 100644
--- a/posix/tst-fnmatch3.c
+++ b/posix/tst-fnmatch3.c
@@ -25,6 +25,8 @@ do_test (void)
     return 1;
   if (fnmatch ("[a[.\0.]]", "a", 0) != FNM_NOMATCH)
     return 1;
+  if (fnmatch ("         ", "**(!()", 0) != FNM_NOMATCH)
+    return 1;
   return 0;
 }