Missing comma before optional parameters gives wrong result

[t-b]

$ git diff .
diff --git a/test-input.ipf b/test-input.ipf
index 07c0b3a..deac92e 100644
--- a/test-input.ipf
+++ b/test-input.ipf
@@ -99,3 +99,7 @@ Function FooParamStruct(s)
     "J
     ASCII85End
 End
+
+Function Dostuff(variable a [variable b])
+
+End
diff --git a/test-input.output.ref b/test-input.output.ref
index f3e7abe..eaa27e5 100644
--- a/test-input.output.ref
+++ b/test-input.output.ref
@@ -100,3 +100,7 @@ static void StaticPic2(){
     // ASCII85End
 };

+variable Dostuff(variable a = defaultValue){
+
+};
+