diff --git a/driver/level2/trmv_U.c b/driver/level2/trmv_U.c
index 90ffb7370..67f9667a2 100644
--- a/driver/level2/trmv_U.c
+++ b/driver/level2/trmv_U.c
@@ -42,7 +42,11 @@
 
 const static FLOAT dp1 = 1.;
 
-int CNAME(BLASLONG m, FLOAT *a, BLASLONG lda, FLOAT *b, BLASLONG incb, FLOAT *buffer){
+int
+#ifndef C_MSVC
+__attribute__((visibility("hidden")))
+#endif
+	CNAME(BLASLONG m, FLOAT *a, BLASLONG lda, FLOAT *b, BLASLONG incb, FLOAT *buffer){
 
   BLASLONG i, is, min_i;
   FLOAT *gemvbuffer = (FLOAT *)buffer;