diff --git a/ChangeLog b/ChangeLog
index fdd4e2b9d..b6c3b320e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2019-08-26  Werner Lemberg  <wl@gnu.org>
+
+	* src/psaux/cffdecode.c (cff_operator_seac): Fix numeric overflow.
+
+	Reported as
+
+	  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=16470
+
 2019-08-26  Werner Lemberg  <wl@gnu.org>
 
 	[type1] Fix `FT_Get_Var_Axis_Flags' (#56804).
diff --git a/src/psaux/cffdecode.c b/src/psaux/cffdecode.c
index 17cccf818..06c6af455 100644
--- a/src/psaux/cffdecode.c
+++ b/src/psaux/cffdecode.c
@@ -330,7 +330,7 @@
     builder->left_bearing.x = 0;
     builder->left_bearing.y = 0;
 
-    builder->pos_x = adx - asb;
+    builder->pos_x = SUB_LONG( adx, asb );
     builder->pos_y = ady;
 
     /* Now load `achar' on top of the base outline. */