Index: gc.h
===================================================================
--- gc.h	(revision 39185)
+++ gc.h	(revision 39186)
@@ -3,9 +3,9 @@
 #define RUBY_GC_H 1
 
 #if defined(__x86_64__) && defined(__GNUC__) && !defined(__native_client__)
-#define SET_MACHINE_STACK_END(p) __asm__ volatile ("movq\t%%rsp, %0" : "=r" (*(p)))
+#define SET_MACHINE_STACK_END(p) __asm__ __volatile__ ("movq\t%%rsp, %0" : "=r" (*(p)))
 #elif defined(__i386) && defined(__GNUC__) && !defined(__native_client__)
-#define SET_MACHINE_STACK_END(p) __asm__ volatile ("movl\t%%esp, %0" : "=r" (*(p)))
+#define SET_MACHINE_STACK_END(p) __asm__ __volatile__ ("movl\t%%esp, %0" : "=r" (*(p)))
 #else
 NOINLINE(void rb_gc_set_stack_end(VALUE **stack_end_p));
 #define SET_MACHINE_STACK_END(p) rb_gc_set_stack_end(p)