diff --git a/compiler/parser.nim b/compiler/parser.nim
index f249b37c84..8fbf033d89 100644
--- a/compiler/parser.nim
+++ b/compiler/parser.nim
@@ -1597,6 +1597,7 @@ proc parseEnum(p: var TParser): PNode =
   optInd(p, result)
   while true:
     var a = parseSymbol(p)
+    if a.kind == nkEmpty: return
     if p.tok.indent >= 0 and p.tok.indent <= p.currInd:
       add(result, a)
       break
diff --git a/tests/parser/twhen_in_enum.nim b/tests/parser/twhen_in_enum.nim
new file mode 100644
index 0000000000..d4a3ea56ac
--- /dev/null
+++ b/tests/parser/twhen_in_enum.nim
@@ -0,0 +1,11 @@
+discard """
+  errormsg: "identifier expected, but found 'keyword when'"
+"""
+
+# bug #2123
+type num = enum
+    NUM_NONE = 0
+    NUM_ALL = 1
+    when defined(macosx): NUM_OSX = 10 # only this differs for real
+    NUM_XTRA = 20
+