diff --git a/ChangeLog b/ChangeLog
index 651f26e..7854293 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2018-10-29  Werner Lemberg  <wl@gnu.org>
+
+	[cff] Fix numeric overflow.
+
+	Reported as
+
+	  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=10988
+
+	* src/cff/cffparse.c (cff_parser_run)
+	[CFF_CONFIG_OPTION_OLD_ENGINE]: Use `NEG_LONG'.
+
 2018-10-27  Alexei Podtelezhnikov  <apodtele@gmail.com>
 
 	[sfnt] Make `head' timestamps unsigned.
diff --git a/src/cff/cffparse.c b/src/cff/cffparse.c
index e152c93..b8b7818 100644
--- a/src/cff/cffparse.c
+++ b/src/cff/cffparse.c
@@ -1259,7 +1259,7 @@
 
           if ( *stack < 0 )
           {
-            num = (FT_ULong)-*stack;
+            num = (FT_ULong)NEG_LONG( *stack );
             neg = 1;
           }
           else