diff --git a/libs/kimath/include/math/box2.h b/libs/kimath/include/math/box2.h
index 2ecff6dc12..d7c4bde375 100644
--- a/libs/kimath/include/math/box2.h
+++ b/libs/kimath/include/math/box2.h
@@ -522,7 +522,7 @@ public:
         }
         else    // size.x < 0:
         {
-            if( m_Size.x > -2 * dx )
+            if( m_Size.x > 2 * dx )
             {
                 // Don't allow deflate to eat more width than we have,
                 m_Pos.x -= m_Size.x / 2;