diff --git a/gcc/fixinc/tests/base/reg_types.h b/gcc/fixinc/tests/base/reg_types.h
index 2a1aad763e4..884494690fd 100644
--- a/gcc/fixinc/tests/base/reg_types.h
+++ b/gcc/fixinc/tests/base/reg_types.h
@@ -3,7 +3,7 @@
 #if defined( OSF_NAMESPACE_A_CHECK )
 typedef struct {
   int stuff, mo_suff;
-} regex_t;
+} __regex_t;
 extern __regex_t    re;
 extern __regoff_t   ro;
 extern __regmatch_t rm;