diff --git a/basis/compiler/cfg/gc-checks/gc-checks.factor b/basis/compiler/cfg/gc-checks/gc-checks.factor
index 1bed3c2bea..e0b7b74207 100644
--- a/basis/compiler/cfg/gc-checks/gc-checks.factor
+++ b/basis/compiler/cfg/gc-checks/gc-checks.factor
@@ -39,9 +39,9 @@ M: insn gc-check-offsets* 2drop ;
     ! Divide a basic block into sections, where every section
     ! other than the first requires a GC check.
     [
-        insns 0 seq [| insns from to |
-            from to insns subseq ,
-            insns to
+        insns 0 seq [| insns' from to |
+            from to insns' subseq ,
+            insns' to
         ] each
         tail ,
     ] { } make ;
diff --git a/basis/compiler/cfg/parallel-copy/parallel-copy.factor b/basis/compiler/cfg/parallel-copy/parallel-copy.factor
index a67bdf15c8..0d2dd26d97 100644
--- a/basis/compiler/cfg/parallel-copy/parallel-copy.factor
+++ b/basis/compiler/cfg/parallel-copy/parallel-copy.factor
@@ -32,9 +32,9 @@ SYMBOLS: locs preds to-do ready ;
 
 :: process-to-do ( b temp: ( src -- dst ) quot: ( dst src -- ) -- )
     b locs get at b = [
-        b temp call :> temp
-        temp b quot call
-        temp b locs get set-at
+        b temp call :> temp'
+        temp' b quot call
+        temp' b locs get set-at
         b ready get push-front
     ] when ; inline