diff --git a/extra/rpn/rpn-tests.factor b/extra/rpn/rpn-tests.factor
new file mode 100644
index 0000000000..c24d5cb244
--- /dev/null
+++ b/extra/rpn/rpn-tests.factor
@@ -0,0 +1,4 @@
+IN: rpn.tests
+USING: rpn lists tools.test ;
+
+[ { 2 } ] [ "4 2 -" rpn-parse rpn-eval list>array ] unit-test
\ No newline at end of file
diff --git a/extra/rpn/rpn.factor b/extra/rpn/rpn.factor
index 7175746862..ba697df8d1 100644
--- a/extra/rpn/rpn.factor
+++ b/extra/rpn/rpn.factor
@@ -10,7 +10,7 @@ TUPLE: push-insn value ;
 GENERIC: eval-insn ( stack insn -- stack )
 
 : binary-op ( stack quot: ( x y -- z ) -- stack )
-    [ uncons uncons ] dip dip cons ; inline
+    [ uncons uncons [ swap ] dip ] dip dip cons ; inline
 
 M: add-insn eval-insn drop [ + ] binary-op ;
 M: sub-insn eval-insn drop [ - ] binary-op ;
@@ -35,11 +35,11 @@ M: push-insn eval-insn value>> swons ;
 : print-stack ( list -- )
     [ number>string print ] leach ;
 
-: rpn-eval ( tokens -- )
-    nil [ eval-insn ] foldl print-stack ;
+: rpn-eval ( tokens -- stack )
+    nil [ eval-insn ] foldl ;
 
 : rpn ( -- )
     "RPN> " write flush
-    readln [ rpn-parse rpn-eval rpn ] when* ;
+    readln [ rpn-parse rpn-eval print-stack rpn ] when* ;
 
 MAIN: rpn