d3d9: Fix type of loop variable.
diff --git a/dlls/d3d9/device.c b/dlls/d3d9/device.c
index 9c50769..c20d98e 100644
--- a/dlls/d3d9/device.c
+++ b/dlls/d3d9/device.c
@@ -61,7 +61,7 @@
     TRACE("(%p) : ReleaseRef to %d\n", This, ref);
 
     if (ref == 0) {
-      int i;
+      unsigned i;
       This->inDestruction = TRUE;
 
       EnterCriticalSection(&d3d9_cs);