diff --git a/posix/regex_internal.c b/posix/regex_internal.c
index bc19243..124f8cc 100644
--- a/posix/regex_internal.c
+++ b/posix/regex_internal.c
@@ -868,7 +868,7 @@ re_string_peek_byte_case (const re_string_t *pstr, int idx)
 }
 
 static unsigned char
-internal_function __attribute ((pure))
+internal_function
 re_string_fetch_byte_case (re_string_t *pstr)
 {
   if (BE (!pstr->mbs_allocated, 1))
-- 
1.7.3.4