diff --git a/basis/cpu/x86/64/64.factor b/basis/cpu/x86/64/64.factor
index 4cd081d324..9fdd4551c9 100644
--- a/basis/cpu/x86/64/64.factor
+++ b/basis/cpu/x86/64/64.factor
@@ -83,10 +83,10 @@ M: x86.64 %mark-deck
 
 M:: x86.64 %load-stack-param ( vreg rep n -- )
     rep return-reg n next-stack@ rep %copy
-    dst rep return-reg rep %copy ;
+    vreg rep return-reg rep %copy ;
 
 M:: x86.64 %store-stack-param ( vreg rep n -- )
-    rep return-reg src rep %copy
+    rep return-reg vreg rep %copy
     n reserved-stack-space + stack@ rep return-reg rep %copy ;
 
 M:: x86.64 %load-reg-param ( vreg rep reg -- )