diff --git a/libkwineffects/kwineffects.cpp b/libkwineffects/kwineffects.cpp
index 41f091f6f0..fe6a27be2e 100644
--- a/libkwineffects/kwineffects.cpp
+++ b/libkwineffects/kwineffects.cpp
@@ -1008,7 +1008,7 @@ WindowQuadList WindowQuadList::splitAtX(double x) const
             ret.append(quad);
             continue;
         }
-        if (quad.left() == quad.right()) { // quad has no size
+        if (quad.top() == quad.bottom() || quad.left() == quad.right()) { // quad has no size
             ret.append(quad);
             continue;
         }
@@ -1040,7 +1040,7 @@ WindowQuadList WindowQuadList::splitAtY(double y) const
             ret.append(quad);
             continue;
         }
-        if (quad.top() == quad.bottom()) { // quad has no size
+        if (quad.top() == quad.bottom() || quad.left() == quad.right()) { // quad has no size
             ret.append(quad);
             continue;
         }