diff --git a/core/stack-checker/row-polymorphism/row-polymorphism.factor b/core/stack-checker/row-polymorphism/row-polymorphism.factor
index 0aea1268f2..5e2b2481ac 100644
--- a/core/stack-checker/row-polymorphism/row-polymorphism.factor
+++ b/core/stack-checker/row-polymorphism/row-polymorphism.factor
@@ -34,7 +34,10 @@ IN: stack-checker.row-polymorphism
     [ vars (check-variable) ] keep ; inline
 
 :: unify-variables ( in-diff in-ok? in-var out-diff out-ok? out-var vars -- ? )
-    { [ in-ok? ] [ out-ok? ] [ in-diff out-diff = ] } 0&& dup [
+    in-ok?
+    out-ok? and
+    in-diff out-diff = and
+    dup [
         in-var  [ in-diff  swap vars adjust-variable ] when*
         out-var [ out-diff swap vars adjust-variable ] when*
     ] when ;
@@ -42,19 +45,19 @@ IN: stack-checker.row-polymorphism
 ! A bit of a hack. If the declared effect is one-sided monomorphic and the actual effect is a
 ! shallow subtype of the root effect, adjust it here
 :: (balance-actual-depth) ( declared actual -- depth/f )
-    {
-        { [ {
-            [ declared in-var>> ]
-            [ declared out-var>> not ]
-            [ actual out>> length declared out>> length < ]
-        } 0&& ] [ declared out>> length actual out>> length - ] }
-        { [ {
-            [ declared in-var>> not ]
-            [ declared out-var>> ]
-            [ actual in>> length declared in>> length < ]
-        } 0&& ] [ declared in>> length actual in>> length - ] }
-        [ f ]
-    } cond ;
+    declared in-var>>
+    declared out-var>> not and
+    actual out>> length declared out>> length < and [
+        declared out>> length actual out>> length -
+    ] [
+        declared in-var>> not
+        declared out-var>> and
+        actual in>> length declared in>> length < and [
+            declared in>> length actual in>> length -
+        ] [
+            f
+        ] if
+    ] if ;
 
 : (balance-by) ( effect n -- effect' )
     "x" <array> swap