diff --git a/extra/math/finance/finance-tests.factor b/extra/math/finance/finance-tests.factor
index fc4ad0d07e..eb4b238f61 100644
--- a/extra/math/finance/finance-tests.factor
+++ b/extra/math/finance/finance-tests.factor
@@ -2,6 +2,8 @@ USING: kernel math math.functions math.finance tools.test ;
 
 IN: math.finance.tests
 
+[ { 1 2 3 4 } ] [ { 1 2 3 4 5 } 1 ema ] unit-test
+
 [ { 2 4 } ] [ { 1 3 5 } 2 sma ] unit-test
 
 [ { 1 3 1 } ] [ { 1 3 2 6 3 } 2 momentum ] unit-test
diff --git a/extra/math/finance/finance.factor b/extra/math/finance/finance.factor
index f1c608bad9..12f58c891b 100644
--- a/extra/math/finance/finance.factor
+++ b/extra/math/finance/finance.factor
@@ -15,7 +15,7 @@ IN: math.finance
 PRIVATE>
 
 : ema ( seq n -- newseq )
-    a swap unclip [ [ dup ] 2dip spin weighted ] accumulate 2nip ;
+    a swap unclip [ swap pick weighted ] accumulate 2nip ;
 
 : sma ( seq n -- newseq )
     clump [ mean ] map ;