diff --git a/ChangeLog b/ChangeLog
index 0e599b9c5..6e11b2a93 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2021-04-02  Ben Wagner  <bungeman@chromium.org>
+
+	[base] Complete `ft_glyphslot_clear`.
+
+	* src/base/ftobjs.c (ft_glyphslot_clear): This function is intended
+	to reset all the values of a glyph slot.  However, it was not
+	resetting the values of the advances and `glyph_index`.  Reset the
+	advances and `glyph_index` to zero.
+
 2021-04-02  Ben Wagner  <bungeman@chromium.org>
 
 	[truetype] Prevent glyph program state from persisting.
diff --git a/src/base/ftobjs.c b/src/base/ftobjs.c
index 56e1360e0..bee301c42 100644
--- a/src/base/ftobjs.c
+++ b/src/base/ftobjs.c
@@ -539,6 +539,8 @@
     ft_glyphslot_free_bitmap( slot );
 
     /* clear all public fields in the glyph slot */
+    slot->glyph_index = 0;
+
     FT_ZERO( &slot->metrics );
     FT_ZERO( &slot->outline );
 
@@ -559,6 +561,8 @@
 
     slot->linearHoriAdvance = 0;
     slot->linearVertAdvance = 0;
+    slot->advance.x         = 0;
+    slot->advance.y         = 0;
     slot->lsb_delta         = 0;
     slot->rsb_delta         = 0;
   }