diff --git a/HISTORY.rst b/HISTORY.rst
index 7743230c81..98847eaca6 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -1,3 +1,7 @@
+2.1.5 (2016-xx-xx)
+==================
+- Backport resize transformation math operation fix (GitLab #319).
+
 2.1.4 (2016-10-28)
 ==================
 - Add missing link to the 2.1.3 release notes in the index file.
diff --git a/mayan/apps/converter/classes.py b/mayan/apps/converter/classes.py
index 72d3eaf61a..f7b8b22bfe 100644
--- a/mayan/apps/converter/classes.py
+++ b/mayan/apps/converter/classes.py
@@ -258,7 +258,7 @@ class TransformationResize(BaseTransformation):
         fit = False
 
         width = int(self.width)
-        height = int(self.height or 1.0 * width * self.aspect)
+        height = int(self.height or 1.0 * width / self.aspect)
 
         factor = 1
         while self.image.size[0] / factor > 2 * width and self.image.size[1] * 2 / factor > 2 * height: