diff --git a/dlls/wined3d/context.c b/dlls/wined3d/context.c
index c3c90eaac1f..2aec7d6bfd3 100644
--- a/dlls/wined3d/context.c
+++ b/dlls/wined3d/context.c
@@ -898,8 +898,8 @@ static void Context_MarkStateDirty(struct wined3d_context *context, DWORD state,
     if (isStateDirty(context, rep)) return;
 
     context->dirtyArray[context->numDirtyEntries++] = rep;
-    idx = rep >> 5;
-    shift = rep & 0x1f;
+    idx = rep / (sizeof(*context->isStateDirty) * CHAR_BIT);
+    shift = rep & ((sizeof(*context->isStateDirty) * CHAR_BIT) - 1);
     context->isStateDirty[idx] |= (1 << shift);
 }
 
@@ -2194,8 +2194,8 @@ static void context_apply_state(struct wined3d_context *context, IWineD3DDeviceI
             for (i = 0; i < context->numDirtyEntries; ++i)
             {
                 DWORD rep = context->dirtyArray[i];
-                DWORD idx = rep >> 5;
-                BYTE shift = rep & 0x1f;
+                DWORD idx = rep / (sizeof(*context->isStateDirty) * CHAR_BIT);
+                BYTE shift = rep & ((sizeof(*context->isStateDirty) * CHAR_BIT) - 1);
                 context->isStateDirty[idx] &= ~(1 << shift);
                 state_table[rep].apply(rep, device->stateBlock, context);
             }
diff --git a/dlls/wined3d/device.c b/dlls/wined3d/device.c
index 5b1ca8c34d8..d0660b43efd 100644
--- a/dlls/wined3d/device.c
+++ b/dlls/wined3d/device.c
@@ -7015,8 +7015,8 @@ void IWineD3DDeviceImpl_MarkStateDirty(IWineD3DDeviceImpl *This, DWORD state) {
         if(isStateDirty(context, rep)) continue;
 
         context->dirtyArray[context->numDirtyEntries++] = rep;
-        idx = rep >> 5;
-        shift = rep & 0x1f;
+        idx = rep / (sizeof(*context->isStateDirty) * CHAR_BIT);
+        shift = rep & ((sizeof(*context->isStateDirty) * CHAR_BIT) - 1);
         context->isStateDirty[idx] |= (1 << shift);
     }
 }
diff --git a/dlls/wined3d/wined3d_private.h b/dlls/wined3d/wined3d_private.h
index b0c28041d7f..b22a7b2a969 100644
--- a/dlls/wined3d/wined3d_private.h
+++ b/dlls/wined3d/wined3d_private.h
@@ -1028,7 +1028,7 @@ struct wined3d_context
      */
     DWORD                   dirtyArray[STATE_HIGHEST + 1]; /* Won't get bigger than that, a state is never marked dirty 2 times */
     DWORD                   numDirtyEntries;
-    DWORD                   isStateDirty[STATE_HIGHEST/32 + 1]; /* Bitmap to find out quickly if a state is dirty */
+    DWORD isStateDirty[STATE_HIGHEST / (sizeof(DWORD) * CHAR_BIT) + 1]; /* Bitmap to find out quickly if a state is dirty */
 
     IWineD3DSurface         *surface;
     IWineD3DSurface *current_rt;
@@ -1614,8 +1614,8 @@ void IWineD3DDeviceImpl_MarkStateDirty(IWineD3DDeviceImpl *This, DWORD state) DE
 
 static inline BOOL isStateDirty(struct wined3d_context *context, DWORD state)
 {
-    DWORD idx = state >> 5;
-    BYTE shift = state & 0x1f;
+    DWORD idx = state / (sizeof(*context->isStateDirty) * CHAR_BIT);
+    BYTE shift = state & ((sizeof(*context->isStateDirty) * CHAR_BIT) - 1);
     return context->isStateDirty[idx] & (1 << shift);
 }