diff --git a/Lib/fontTools/ttLib/tables/_g_l_y_f.py b/Lib/fontTools/ttLib/tables/_g_l_y_f.py
index 6d3c80b7d9..a9f0387481 100644
--- a/Lib/fontTools/ttLib/tables/_g_l_y_f.py
+++ b/Lib/fontTools/ttLib/tables/_g_l_y_f.py
@@ -138,6 +138,9 @@ def toXML(self, writer, ttFont, splitGlyphs=False):
 			path, ext = os.path.splitext(writer.file.name)
 			existingGlyphFiles = set()
 		for glyphName in glyphNames:
+			if glyphName not in self:
+				log.warning("glyph '%s' does not exist in glyf table", glyphName)
+				continue
 			glyph = self[glyphName]
 			if glyph.numberOfContours:
 				if splitGlyphs: