diff --git a/rostests/apitests/w32knapi/w32knapi.rbuild b/rostests/apitests/w32knapi/w32knapi.rbuild
index 3f662ed2263..be94a19a2b2 100644
--- a/rostests/apitests/w32knapi/w32knapi.rbuild
+++ b/rostests/apitests/w32knapi/w32knapi.rbuild
@@ -9,6 +9,7 @@
 	<library>advapi32</library>
 	<library>w32kdll</library>
 	<library>dbghelp</library>
+	<compilerflag compilerset="gcc">-fms-extensions</compilerflag>
 	<file>w32knapi.c</file>
 	<file>osver.c</file>
 	<file>testlist.c</file>