diff --git a/CHANGES.rst b/CHANGES.rst
index 9a874a8e..18751ea1 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -10,7 +10,9 @@ New:
 
 Fixes:
 
-- *add item here*
+- Workarround for method getImageSize.
+  Prevent returning (-1, -1) as the size of the image.
+  [andreesg]
 
 
 3.0.5 (2015-11-26)
diff --git a/plone/namedfile/file.py b/plone/namedfile/file.py
index 5c86215f..61eeac38 100644
--- a/plone/namedfile/file.py
+++ b/plone/namedfile/file.py
@@ -463,4 +463,9 @@ def getFirstBytes(self, start=0, length=IMAGE_INFO_BYTES):
 
     def getImageSize(self):
         """See interface `IImage`"""
+        if (self._width, self._height) != (-1, -1):
+            return (self._width, self._height)
+
+        res = getImageInfo(self.data)
+        contentType, self._width, self._height = res
         return (self._width, self._height)