diff --git a/gcc/config/i386/linux.h b/gcc/config/i386/linux.h
index 8b467d6b81b..8cfe5445e03 100644
--- a/gcc/config/i386/linux.h
+++ b/gcc/config/i386/linux.h
@@ -17,6 +17,9 @@
 
 #endif
 
+/* This is tested by i386gas.h.  */
+#define YES_UNDERSCORES
+
 #include "i386gas.h"
 
 /* Specify predefined symbols in preprocessor.  */