diff --git a/src/tools/vppapigen/vppapigen_json.py b/src/tools/vppapigen/vppapigen_json.py
index ba32e28..0a1a3d3 100644
--- a/src/tools/vppapigen/vppapigen_json.py
+++ b/src/tools/vppapigen/vppapigen_json.py
@@ -77,7 +77,8 @@
             c = {}
             c["crc"] = "{0:#0{1}x}".format(t.crc, 10)
             c["options"] = t.options
-            c["comment"] = t.comment
+            if t.comment:
+                c["comment"] = t.comment
             d.append(c)
 
         r.append(d)