diff --git a/server/red_worker.h b/server/red_worker.h
index ae2eaeec..b4e2ed2e 100644
--- a/server/red_worker.h
+++ b/server/red_worker.h
@@ -23,12 +23,14 @@
 
 static inline void set_bit(int index, uint32_t *addr)
 {
-    __asm__ __volatile__ ("lock btsl %1, %0": : "m" (*addr), "r" (index));
+    uint32_t mask = 1 << index;
+    __sync_or_and_fetch(addr, mask);
 }
 
 static inline void clear_bit(int index, uint32_t *addr)
 {
-    __asm__ __volatile__ ("lock btrl %1, %0": : "m" (*addr), "r" (index));
+    uint32_t mask = ~(1 << index);
+    __sync_and_and_fetch(addr, mask);
 }
 
 static inline int test_bit(int index, uint32_t val)