diff --git a/core/assocs/assocs.factor b/core/assocs/assocs.factor
index be796ca554..b613147f29 100755
--- a/core/assocs/assocs.factor
+++ b/core/assocs/assocs.factor
@@ -158,6 +158,9 @@ M: assoc value-at* swap [ = nip ] curry assoc-find nip ;
 : zip ( keys values -- alist )
     2array flip ; inline
 
+: unzip ( assoc -- keys values )
+    dup assoc-empty? [ drop { } { } ] [ >alist flip first2 ] if ;
+
 : search-alist ( key alist -- pair i )
     [ first = ] with find swap ; inline
 
diff --git a/extra/koszul/koszul.factor b/extra/koszul/koszul.factor
index 37c2137433..2b67a3755e 100755
--- a/extra/koszul/koszul.factor
+++ b/extra/koszul/koszul.factor
@@ -184,7 +184,7 @@ DEFER: (d)
     [ length ] keep [ (graded-ker/im-d) ] curry map ;
 
 : graded-betti ( generators -- seq )
-    basis graded graded-ker/im-d flip first2 but-last 0 prefix v- ;
+    basis graded graded-ker/im-d unzip but-last 0 prefix v- ;
 
 ! Bi-graded for two-step complexes
 : (bigraded-ker/im-d) ( u-deg z-deg bigraded-basis -- null/rank )