diff --git a/ChangeLog b/ChangeLog
index 7340978ce..afe63fc84 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2017-10-20  Alexei Podtelezhnikov  <apodtele@gmail.com>
+
+	[smooth] Improve complex rendering at high ppem.
+
+	At large sizes almost but not exactly horizontal segments can quickly
+	drain the rendering pool. This patch at least avoids filling the pool
+	with trivial cells. Beyond this, we can only increase the pool size.
+
+	Reported, analyzed, and tested by Colin Fahey.
+
+	* src/smooth/ftgrays.c (gray_set_cell): Do not record trivial cells.
+
 2017-10-20  Alexei Podtelezhnikov  <apodtele@gmail.com>
 
 	[base] Improve tracing in FT_Load_Glyph, FT_*_Size.
@@ -43,7 +55,7 @@
 2017-10-14  Alexei Podtelezhnikov  <apodtele@gmail.com>
 
 	* builds/windows/ftdebug.c (FT_Message): Print to stderr.
-        * builds/wince/ftdebug.c (FT_Message): Ditto.
+	* builds/wince/ftdebug.c (FT_Message): Ditto.
 
 2017-10-14  Behdad Esfahbod  <behdad@behdad.org>
 
diff --git a/src/smooth/ftgrays.c b/src/smooth/ftgrays.c
index e84e38d85..fa488ecb9 100644
--- a/src/smooth/ftgrays.c
+++ b/src/smooth/ftgrays.c
@@ -582,8 +582,8 @@ typedef ptrdiff_t  FT_PtrDist;
     if ( ex < ras.min_ex )
       ex = ras.min_ex - 1;
 
-    /* record the current one if it is valid */
-    if ( !ras.invalid )
+    /* record the current one if it is substantial and valid */
+    if ( ( ras.area || ras.cover ) && !ras.invalid )
       gray_record_cell( RAS_VAR );
 
     ras.area  = 0;