diff --git a/extra/math/similarity/similarity-tests.factor b/extra/math/similarity/similarity-tests.factor
index d8be58b6c3..0fd32dc7e1 100644
--- a/extra/math/similarity/similarity-tests.factor
+++ b/extra/math/similarity/similarity-tests.factor
@@ -1,7 +1,7 @@
 ! Copyright (C) 2012 John Benediktsson
 ! See http://factorcode.org/license.txt for BSD license
 
-USING: math.functions math.similarity tools.test ;
+USING: math.functions math.similarity math.vectors tools.test ;
 
 IN: math.similarity.tests
 
@@ -15,4 +15,6 @@ CONSTANT: b { 0 0 0 0 2 3 1 }
 { t } [ a b pearson-similarity 0.2376861940759582 1e-10 ~ ] unit-test
 
 { t } [ a a cosine-similarity 1.0 1e-10 ~ ] unit-test
-{ t } [ a b cosine-similarity 0.5472455591261534 1e-10 ~ ] unit-test
+{ t } [ a a vneg cosine-similarity -1.0 1e-10 ~ ] unit-test
+{ t } [ a b cosine-similarity 0.0944911182523068 1e-10 ~ ] unit-test
+
diff --git a/extra/math/similarity/similarity.factor b/extra/math/similarity/similarity.factor
index 133537ac4d..1fdc82cfdb 100644
--- a/extra/math/similarity/similarity.factor
+++ b/extra/math/similarity/similarity.factor
@@ -12,4 +12,4 @@ IN: math.similarity
     over length 3 < [ 2drop 1.0 ] [ population-corr 0.5 * 0.5 + ] if ;
 
 : cosine-similarity ( a b -- n )
-    [ v* sum ] [ [ norm ] bi@ * ] 2bi / 0.5 * 0.5 + ;
+    [ v* sum ] [ [ norm ] bi@ * ] 2bi / ;