diff --git a/core/effects/effects-tests.factor b/core/effects/effects-tests.factor
index 068a597994..707396b6ed 100644
--- a/core/effects/effects-tests.factor
+++ b/core/effects/effects-tests.factor
@@ -56,5 +56,8 @@ IN: effects.tests
 { ( x -- ) } [ ( a b -- ) curry-effect ] unit-test
 
 ! test unnamed types
-{ ( _: fixnum -- _: float ) } [ ( :fixnum -- :float ) ] unit-test
-{ ( _: union{ fixnum bignum } -- ) } [ ( :union{ fixnum bignum } -- ) ] unit-test
+{ ( :fixnum -- :float ) } [ ( :fixnum -- :float ) ] unit-test
+{ ( :union{ fixnum bignum } -- ) } [ ( :union{ fixnum bignum } -- ) ] unit-test
+
+{ "( :( :integer -- :integer ) :float -- :bignum )" }
+[ ( :( :integer -- :integer ) :float -- :bignum ) unparse ] unit-test
diff --git a/core/effects/effects.factor b/core/effects/effects.factor
index 8765e90415..010d4d4d97 100644
--- a/core/effects/effects.factor
+++ b/core/effects/effects.factor
@@ -54,7 +54,12 @@ M: string effect>string ;
 M: object effect>string drop "object" ;
 M: word effect>string name>> ;
 M: integer effect>string number>string ;
-M: pair effect>string first2-unsafe [ effect>string ] bi@ ": " glue ;
+M: pair effect>string
+    first2-unsafe over [
+        [ effect>string ] bi@ ": " glue
+    ] [
+        nip effect>string ":" prepend
+    ] if ;
 
 : stack-picture ( seq -- string )
     [ [ effect>string % CHAR: \s , ] each ] "" make ;
diff --git a/core/effects/parser/parser.factor b/core/effects/parser/parser.factor
index 46e635d289..46629023ed 100644
--- a/core/effects/parser/parser.factor
+++ b/core/effects/parser/parser.factor
@@ -35,7 +35,7 @@ ERROR: bad-standalone-effect obj ;
     dup parsing-word? [
         ?execute-parsing dup length 1 =
         [ first ] [ bad-standalone-effect ] if
-    ] when "_" swap 2array ;
+    ] when f swap 2array ;
 PRIVATE>
 
 : parse-effect-token ( first? var end -- var more? )