diff --git a/ChangeLog b/ChangeLog
index e986e2794..02952866f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2015-02-25  Werner Lemberg  <wl@gnu.org>
+
+	Change dimension fields in `FTC_ImageTypeRec' to unsigned type.
+
+	This doesn't break ABI.
+
+	* include/ftcache.h (FTC_ImageTypeRec): Use unsigned types for
+	`width' and `height'.
+
+	* docs/CHANGES: Document it.
+
 2015-02-25  Werner Lemberg  <wl@gnu.org>
 
 	[cache] Don't use `labs'.
diff --git a/docs/CHANGES b/docs/CHANGES
index 3a0dcd2e1..352563df4 100644
--- a/docs/CHANGES
+++ b/docs/CHANGES
@@ -1,5 +1,5 @@
 
-CHANGES BETWEEN 2.5.5 and 2.5.6
+CHANGES BETWEEN 2.5.5 and 2.6
 
   II. IMPORTANT CHANGES
 
@@ -22,6 +22,17 @@ CHANGES BETWEEN 2.5.5 and 2.5.6
       used from multiple threads at the same time.
 
 
+  III. MISCELLANEOUS
+
+    - Some  fields  in  the  `FTC_ImageTypeRec'  structure  have  been
+      changed from signed to unsigned  type, which better reflects the
+      actual usage.  It is also an additional means to protect against
+      malformed input.
+
+      This  change doesn't  break  the ABI;  however,  it might  cause
+      compiler warnings.
+
+
 ======================================================================
 
 CHANGES BETWEEN 2.5.4 and 2.5.5
diff --git a/include/ftcache.h b/include/ftcache.h
index c1a755599..68525bb82 100644
--- a/include/ftcache.h
+++ b/include/ftcache.h
@@ -667,8 +667,8 @@ FT_BEGIN_HEADER
   typedef struct  FTC_ImageTypeRec_
   {
     FTC_FaceID  face_id;
-    FT_Int      width;
-    FT_Int      height;
+    FT_UInt     width;
+    FT_UInt     height;
     FT_Int32    flags;
 
   } FTC_ImageTypeRec;