diff --git a/src/core/SkBitmap.cpp b/src/core/SkBitmap.cpp
index 2635e13..9a116df 100644
--- a/src/core/SkBitmap.cpp
+++ b/src/core/SkBitmap.cpp
@@ -340,7 +340,7 @@
 }
 
 void SkBitmap::lockPixels() const {
-    if (NULL != fPixelRef && 1 == ++fPixelLockCount) {
+    if (NULL != fPixelRef && 0 == sk_atomic_inc(&fPixelLockCount)) {
         fPixelRef->lockPixels();
         this->updatePixelsFromRef();
     }
@@ -350,7 +350,7 @@
 void SkBitmap::unlockPixels() const {
     SkASSERT(NULL == fPixelRef || fPixelLockCount > 0);
 
-    if (NULL != fPixelRef && 0 == --fPixelLockCount) {
+    if (NULL != fPixelRef && 1 == sk_atomic_dec(&fPixelLockCount)) {
         fPixelRef->unlockPixels();
         this->updatePixelsFromRef();
     }