diff --git a/target-i386/helper.c b/target-i386/helper.c
index e61b05dc5c..d7cb6849b4 100644
--- a/target-i386/helper.c
+++ b/target-i386/helper.c
@@ -1796,7 +1796,7 @@ void helper_rdtsc(void)
 {
     uint64_t val;
 #if defined(__i386__) || defined(__x86_64__)
-    asm("rdtsc" : "=A" (val));
+    asm volatile ("rdtsc" : "=A" (val));
 #else
     /* better than nothing: the time increases */
     val = emu_time++;
diff --git a/vl.c b/vl.c
index ed5c380151..24895508d0 100644
--- a/vl.c
+++ b/vl.c
@@ -341,7 +341,7 @@ int64_t cpu_get_real_ticks(void)
 int64_t cpu_get_real_ticks(void)
 {
     int64_t val;
-    asm("rdtsc" : "=A" (val));
+    asm volatile ("rdtsc" : "=A" (val));
     return val;
 }