diff --git a/basis/compiler/cfg/loop-detection/loop-detection.factor b/basis/compiler/cfg/loop-detection/loop-detection.factor
index d8fc92aaa6..5fd613c326 100644
--- a/basis/compiler/cfg/loop-detection/loop-detection.factor
+++ b/basis/compiler/cfg/loop-detection/loop-detection.factor
@@ -27,18 +27,18 @@ SYMBOLS: visited active ;
 DEFER: find-loop-headers
 
 : visit-edge ( from to -- )
-    dup active get key?
+    dup active get in?
     [ record-back-edge ]
     [ nip find-loop-headers ]
     if ;
 
 : find-loop-headers ( bb -- )
-    dup visited get key? [ drop ] [
+    dup visited get in? [ drop ] [
         {
-            [ visited get conjoin ]
-            [ active get conjoin ]
+            [ visited get adjoin ]
+            [ active get adjoin ]
             [ dup successors>> [ visit-edge ] with each ]
-            [ active get delete-at ]
+            [ active get delete ]
         } cleave
     ] if ;
 
@@ -70,8 +70,8 @@ SYMBOL: loop-nesting
 : detect-loops ( cfg -- cfg' )
     needs-predecessors
     H{ } clone loops set
-    H{ } clone visited set
-    H{ } clone active set
+    HS{ } clone visited set
+    HS{ } clone active set
     H{ } clone loop-nesting set
     dup entry>> find-loop-headers process-loop-headers compute-loop-nesting ;
 
diff --git a/basis/compiler/cfg/rpo/rpo.factor b/basis/compiler/cfg/rpo/rpo.factor
index 711657e8e5..09889c59d8 100644
--- a/basis/compiler/cfg/rpo/rpo.factor
+++ b/basis/compiler/cfg/rpo/rpo.factor
@@ -5,16 +5,14 @@ assocs fry compiler.cfg compiler.cfg.instructions ;
 FROM: namespaces => set ;
 IN: compiler.cfg.rpo
 
-SYMBOL: visited
-
-: post-order-traversal ( bb -- )
-    dup visited get key? [ drop ] [
-        dup visited get conjoin
+: post-order-traversal ( visited bb -- visited' )
+    dup pick in? [ drop ] [
+        dup pick adjoin
         [
             successors>> <reversed>
             [ post-order-traversal ] each
         ] [ , ] bi
-    ] if ;
+    ] if ; inline recursive
 
 : number-blocks ( blocks -- )
     dup length iota <reversed>
@@ -23,8 +21,8 @@ SYMBOL: visited
 : post-order ( cfg -- blocks )
     dup post-order>> [ ] [
         [
-            H{ } clone visited set
-            dup entry>> post-order-traversal
+            HS{ } clone over entry>>
+            post-order-traversal drop
         ] { } make dup number-blocks
         >>post-order post-order>>
     ] ?if ;
diff --git a/basis/compiler/cfg/utilities/utilities.factor b/basis/compiler/cfg/utilities/utilities.factor
index 820871ea05..72bbcf4feb 100644
--- a/basis/compiler/cfg/utilities/utilities.factor
+++ b/basis/compiler/cfg/utilities/utilities.factor
@@ -18,18 +18,16 @@ IN: compiler.cfg.utilities
         [ first ##branch? ]
     } 1&& ;
 
-SYMBOL: visited
-
-: (skip-empty-blocks) ( bb -- bb' )
-    dup visited get key? [
+: (skip-empty-blocks) ( visited bb -- visited' bb' )
+    dup pick in? [
         dup empty-block? [
-            dup visited get conjoin
+            dup pick adjoin
             successors>> first (skip-empty-blocks)
         ] when
-    ] unless ;
+    ] unless ; inline recursive
 
 : skip-empty-blocks ( bb -- bb' )
-    H{ } clone visited [ (skip-empty-blocks) ] with-variable ;
+    [ HS{ } clone ] dip (skip-empty-blocks) nip ;
 
 :: update-predecessors ( from to bb -- )
     ! Whenever 'from' appears in the list of predecessors of 'to'
diff --git a/basis/compiler/tree/def-use/simplified/simplified.factor b/basis/compiler/tree/def-use/simplified/simplified.factor
index 0061e8cffb..b93c013dfa 100644
--- a/basis/compiler/tree/def-use/simplified/simplified.factor
+++ b/basis/compiler/tree/def-use/simplified/simplified.factor
@@ -15,15 +15,15 @@ TUPLE: real-usage value node ;
 SYMBOLS: visited accum ;
 
 : if-not-visited ( value quot -- )
-    over visited get key?
-    [ 2drop ] [ over visited get conjoin call ] if ; inline
+    over visited get in?
+    [ 2drop ] [ over visited get adjoin call ] if ; inline
 
 : with-simplified-def-use ( quot -- real-usages )
     [
-        H{ } clone visited set
-        H{ } clone accum set
+        HS{ } clone visited set
+        HS{ } clone accum set
         call
-        accum get keys
+        accum get members
     ] with-scope ; inline
 
 PRIVATE>
@@ -54,7 +54,7 @@ M: #phi actually-defined-by*
     ] with each ;
 
 M: node actually-defined-by*
-    real-usage boa accum get conjoin ;
+    real-usage boa accum get adjoin ;
 
 : actually-defined-by ( value -- real-usages )
     [ (actually-defined-by) ] with-simplified-def-use ;
@@ -88,7 +88,7 @@ M: #phi actually-used-by*
 M: #recursive actually-used-by* 2drop ;
 
 M: node actually-used-by*
-    real-usage boa accum get conjoin ;
+    real-usage boa accum get adjoin ;
 
 : actually-used-by ( value -- real-usages )
     [ (actually-used-by) ] with-simplified-def-use ;