diff --git a/libkwineffects/kwineffects.cpp b/libkwineffects/kwineffects.cpp
index 3647542bb6..33e295cbd9 100644
--- a/libkwineffects/kwineffects.cpp
+++ b/libkwineffects/kwineffects.cpp
@@ -1011,7 +1011,7 @@ 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;
         }
@@ -1043,7 +1043,7 @@ 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;
         }