diff --git a/ChangeLog b/ChangeLog
index f1ca0f516..f290bd535 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2017-07-05  Werner Lemberg  <wl@gnu.org>
+
+	* src/truetype/ttgxvar.c (FT_Stream_SeekSet): Fix warning (#51395).
+
 2017-07-04  Werner Lemberg  <wl@gnu.org>
 
 	[truetype] Prevent address overflow (#51365).
diff --git a/src/truetype/ttgxvar.c b/src/truetype/ttgxvar.c
index 9125afd10..68458362e 100644
--- a/src/truetype/ttgxvar.c
+++ b/src/truetype/ttgxvar.c
@@ -60,10 +60,11 @@
 
 #define FT_Stream_FTell( stream )                         \
           (FT_ULong)( (stream)->cursor - (stream)->base )
-#define FT_Stream_SeekSet( stream, off )                                  \
-          (stream)->cursor = ( (off) < (stream)->limit - (stream)->base ) \
-                               ? (stream)->base + (off)                   \
-                               : (stream)->limit
+#define FT_Stream_SeekSet( stream, off )                               \
+          (stream)->cursor =                                           \
+            ( (off) < (FT_ULong)( (stream)->limit - (stream)->base ) ) \
+                        ? (stream)->base + (off)                       \
+                        : (stream)->limit
 
 
   /*************************************************************************/