diff --git a/extra/math/physics/pos/pos.factor b/extra/math/physics/pos/pos.factor
index 1582c42108..69155686c8 100644
--- a/extra/math/physics/pos/pos.factor
+++ b/extra/math/physics/pos/pos.factor
@@ -1,5 +1,17 @@
 
+USING: kernel sequences multi-methods accessors math.vectors ;
+
 IN: math.physics.pos
 
 TUPLE: pos pos ;
 
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+GENERIC: distance ( a b -- c )
+
+METHOD: distance { sequence sequence } v- norm ;
+
+METHOD: distance { pos pos } [ pos>> ] bi@ distance ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+