diff --git a/src/detectors/builtin/argCopyMutation.ts b/src/detectors/builtin/argCopyMutation.ts
index 14ee0d89..a89fcfc0 100644
--- a/src/detectors/builtin/argCopyMutation.ts
+++ b/src/detectors/builtin/argCopyMutation.ts
@@ -7,7 +7,7 @@ import {
   funName,
 } from "../../internals/tact";
 import { hasInExpressions } from "../../internals/tact/iterators";
-import { intersection } from "../../internals/util";
+import { intersectLists } from "../../internals/util";
 import { MistiTactWarning, Severity } from "../../internals/warnings";
 import { ASTDetector } from "../detector";
 import {
@@ -202,7 +202,7 @@ export class ArgCopyMutation extends ASTDetector {
   ): Map<string, AstStatement[]> {
     const mutations = collectMutations(stmt, { flatStmts: true });
     const foundMutations = mutations
-      ? intersection(argNames, mutationNames(mutations.mutatedLocals))
+      ? intersectLists(argNames, mutationNames(mutations.mutatedLocals))
       : [];
     return foundMutations.reduce((mutationMap, argName) => {
       const existingStatements = mutationMap.get(argName) || [];
diff --git a/src/detectors/builtin/inheritedStateMutation.ts b/src/detectors/builtin/inheritedStateMutation.ts
index d5e82d1b..e8cadd35 100644
--- a/src/detectors/builtin/inheritedStateMutation.ts
+++ b/src/detectors/builtin/inheritedStateMutation.ts
@@ -5,7 +5,7 @@ import {
   collectMutations,
   mutationNames,
 } from "../../internals/tact";
-import { intersection } from "../../internals/util";
+import { intersectLists } from "../../internals/util";
 import { MistiTactWarning, Severity } from "../../internals/warnings";
 import { ASTDetector } from "../detector";
 import { AstStatement, AstNode } from "@tact-lang/compiler/dist/grammar/ast";
@@ -99,7 +99,7 @@ export class InheritedStateMutation extends ASTDetector {
   ): MistiTactWarning[] {
     const mutations = collectMutations(stmt);
     const foundMutations = mutations
-      ? intersection(
+      ? intersectLists(
           inheritedFieldNames,
           mutationNames(mutations.mutatedFields),
         )
diff --git a/src/detectors/builtin/neverAccessedVariables.ts b/src/detectors/builtin/neverAccessedVariables.ts
index f7821b2d..37e07a79 100644
--- a/src/detectors/builtin/neverAccessedVariables.ts
+++ b/src/detectors/builtin/neverAccessedVariables.ts
@@ -8,7 +8,7 @@ import {
   forEachExpression,
 } from "../../internals/tact";
 import { Transfer } from "../../internals/transfer";
-import { mergeSets, isSubsetOf } from "../../internals/util";
+import { mergeSets, isSetSubsetOf } from "../../internals/util";
 import { unreachable } from "../../internals/util";
 import { MistiTactWarning, Severity } from "../../internals/warnings";
 import { DataflowDetector, WarningsBehavior } from "../detector";
@@ -59,8 +59,8 @@ class VariableUsageLattice implements JoinSemilattice<VariableState> {
   leq(a: VariableState, b: VariableState): boolean {
     return (
       [...a.declared.extract()].every((x) => b.declared.has(x)) &&
-      isSubsetOf(a.accessed, b.accessed) &&
-      isSubsetOf(a.written, b.written)
+      isSetSubsetOf(a.accessed, b.accessed) &&
+      isSetSubsetOf(a.written, b.written)
     );
   }
 }
diff --git a/src/detectors/builtin/stringReceiversOverlap.ts b/src/detectors/builtin/stringReceiversOverlap.ts
index fb4d2282..6bf40e21 100644
--- a/src/detectors/builtin/stringReceiversOverlap.ts
+++ b/src/detectors/builtin/stringReceiversOverlap.ts
@@ -3,7 +3,7 @@ import { JoinSemilattice } from "../../internals/lattice";
 import { WorklistSolver } from "../../internals/solver/";
 import { forEachExpression, forEachStatement } from "../../internals/tact";
 import { Transfer } from "../../internals/transfer";
-import { mergeSets, isSubsetOf } from "../../internals/util";
+import { mergeSets, isSetSubsetOf } from "../../internals/util";
 import { MistiTactWarning, Severity } from "../../internals/warnings";
 import { DataflowDetector } from "../detector";
 import {
@@ -56,8 +56,8 @@ class TaintLattice implements JoinSemilattice<TaintState> {
 
   leq(a: TaintState, b: TaintState): boolean {
     return (
-      isSubsetOf(a.argTaint, b.argTaint) &&
-      isSubsetOf(a.literalTaint, b.literalTaint)
+      isSetSubsetOf(a.argTaint, b.argTaint) &&
+      isSetSubsetOf(a.literalTaint, b.literalTaint)
     );
   }
 }
diff --git a/src/internals/util.ts b/src/internals/util.ts
index 53d6cad9..e4e6a9d9 100644
--- a/src/internals/util.ts
+++ b/src/internals/util.ts
@@ -7,25 +7,32 @@
 import { InternalException } from "./exceptions";
 import path from "path";
 
-/**
- * Intersection of two lists.
- */
-export const intersection = <T>(l1: T[], l2: T[]): T[] =>
-  l1.filter((element) => l2.includes(element));
-
 export const mergeSets = <T>(lhs: Set<T>, rhs: Set<T>): Set<T> =>
   new Set([...lhs, ...rhs]);
-export const isSubsetOf = <T>(lhs: Set<T>, rhs: Set<T>): boolean =>
+export const isSetSubsetOf = <T>(lhs: Set<T>, rhs: Set<T>): boolean =>
   [...lhs].every((elem) => rhs.has(elem));
+export const intersectSets = <T>(setA: Set<T>, setB: Set<T>): Set<T> =>
+  new Set([...setA].filter((item) => setB.has(item)));
 
 export const mergeLists = <T>(lhs: T[], rhs: T[]): T[] => [...lhs, ...rhs];
 export const isListSubsetOf = <T>(lhs: T[], rhs: T[]): boolean =>
   lhs.every((elem) => rhs.includes(elem));
+export const intersectLists = <T>(l1: T[], l2: T[]): T[] =>
+  l1.filter((element) => l2.includes(element));
 
 export const mergeMaps = <K, V>(lhs: Map<K, V>, rhs: Map<K, V>): Map<K, V> =>
   new Map([...lhs, ...rhs]);
 export const isMapSubsetOf = <K, V>(lhs: Map<K, V>, rhs: Map<K, V>): boolean =>
   [...lhs].every(([key, value]) => rhs.has(key) && rhs.get(key) === value);
+export const intersectMaps = <K, V>(
+  mapA: Map<K, V>,
+  mapB: Map<K, V>,
+): Map<K, V> =>
+  new Map(
+    [...mapA].filter(
+      ([key, value]) => mapB.has(key) && mapB.get(key) === value,
+    ),
+  );
 
 /**
  * Unreachable case for exhaustive checking.