diff --git a/extra/math/quaternions/quaternions.factor b/extra/math/quaternions/quaternions.factor
index b7bfd92a1b..3c450f1c05 100755
--- a/extra/math/quaternions/quaternions.factor
+++ b/extra/math/quaternions/quaternions.factor
@@ -74,5 +74,4 @@ PRIVATE>
     >r -0.5 * dup cos c>q swap sin r> n*v v- ;
 
 : euler ( phi theta psi -- q )
-    qk (euler) >r qj (euler) >r qi (euler) r> q* r> q* ;
-
+  [ qi (euler) ] [ qj (euler) ] [ qk (euler) ] tri* q* q* ;