diff --git a/driver/utils.h b/driver/utils.h
index b2a1ed9a5..bd5288790 100644
--- a/driver/utils.h
+++ b/driver/utils.h
@@ -123,7 +123,7 @@ RETCODE fillOutputU16String(const STRING & value,
     PTR out_value, LENGTH out_value_max_length, LENGTH * out_value_length)
 {
     LENGTH size_without_zero = static_cast<LENGTH>(value.size());
-    const size_t typeSize = sizeof(STRING::value_type);
+    const size_t typeSize = sizeof(typename STRING::value_type);
 
     if (out_value_length)
         *out_value_length = size_without_zero * typeSize;