diff --git a/Userland/Libraries/LibJS/Runtime/SetPrototype.cpp b/Userland/Libraries/LibJS/Runtime/SetPrototype.cpp
index accfeb5a3c..8b0bcb3420 100644
--- a/Userland/Libraries/LibJS/Runtime/SetPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/SetPrototype.cpp
@@ -229,21 +229,25 @@ static ThrowCompletionOr<SetRecord> get_set_record(VM& vm, Value value)
     // 6. Let intSize be ! ToIntegerOrInfinity(numSize).
     auto integer_size = MUST(number_size.to_integer_or_infinity(vm));
 
-    // 7. Let has be ? Get(obj, "has").
+    // 7. If intSize < 0, throw a RangeError exception.
+    if (integer_size < 0)
+        return vm.throw_completion<RangeError>(ErrorType::NumberIsNegative, "size"sv);
+
+    // 8. Let has be ? Get(obj, "has").
     auto has = TRY(object.get(vm.names.has));
 
-    // 8. If IsCallable(has) is false, throw a TypeError exception.
+    // 9. If IsCallable(has) is false, throw a TypeError exception.
     if (!has.is_function())
         return vm.throw_completion<TypeError>(ErrorType::NotAFunction, TRY_OR_THROW_OOM(vm, has.to_string_without_side_effects()));
 
-    // 9. Let keys be ? Get(obj, "keys").
+    // 10. Let keys be ? Get(obj, "keys").
     auto keys = TRY(object.get(vm.names.keys));
 
-    // 10. If IsCallable(keys) is false, throw a TypeError exception.
+    // 11. If IsCallable(keys) is false, throw a TypeError exception.
     if (!keys.is_function())
         return vm.throw_completion<TypeError>(ErrorType::NotAFunction, TRY_OR_THROW_OOM(vm, keys.to_string_without_side_effects()));
 
-    // 11. Return a new Set Record { [[Set]]: obj, [[Size]]: intSize, [[Has]]: has, [[Keys]]: keys }.
+    // 12. Return a new Set Record { [[Set]]: obj, [[Size]]: intSize, [[Has]]: has, [[Keys]]: keys }.
     return SetRecord { .set = object, .size = integer_size, .has = has.as_function(), .keys = keys.as_function() };
 }
 
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.difference.js b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.difference.js
index 7547ce84ec..dc5111b895 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.difference.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.difference.js
@@ -1,3 +1,11 @@
+describe("errors", () => {
+    test("called with negative size", () => {
+        expect(() => {
+            new Set().difference({ size: -1 });
+        }).toThrowWithMessage(RangeError, "size must not be negative");
+    });
+});
+
 test("basic functionality", () => {
     expect(Set.prototype.difference).toHaveLength(1);
 
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.intersection.js b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.intersection.js
index 98ce3f1c96..502c93c2d8 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.intersection.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.intersection.js
@@ -1,3 +1,11 @@
+describe("errors", () => {
+    test("called with negative size", () => {
+        expect(() => {
+            new Set().intersection({ size: -1 });
+        }).toThrowWithMessage(RangeError, "size must not be negative");
+    });
+});
+
 test("basic functionality", () => {
     expect(Set.prototype.intersection).toHaveLength(1);
 
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.isDisjointFrom.js b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.isDisjointFrom.js
index b506e65196..261cd8c027 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.isDisjointFrom.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.isDisjointFrom.js
@@ -1,3 +1,11 @@
+describe("errors", () => {
+    test("called with negative size", () => {
+        expect(() => {
+            new Set().isDisjointFrom({ size: -1 });
+        }).toThrowWithMessage(RangeError, "size must not be negative");
+    });
+});
+
 test("basic functionality", () => {
     expect(Set.prototype.isDisjointFrom).toHaveLength(1);
 
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.isSubsetOf.js b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.isSubsetOf.js
index d5dc6ab9d0..ee0ef0c1ed 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.isSubsetOf.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.isSubsetOf.js
@@ -1,3 +1,11 @@
+describe("errors", () => {
+    test("called with negative size", () => {
+        expect(() => {
+            new Set().isSubsetOf({ size: -1 });
+        }).toThrowWithMessage(RangeError, "size must not be negative");
+    });
+});
+
 test("basic functionality", () => {
     expect(Set.prototype.isSubsetOf).toHaveLength(1);
 
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.isSupersetOf.js b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.isSupersetOf.js
index 3475ab2787..bd5a3b046c 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.isSupersetOf.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.isSupersetOf.js
@@ -1,3 +1,11 @@
+describe("errors", () => {
+    test("called with negative size", () => {
+        expect(() => {
+            new Set().isSupersetOf({ size: -1 });
+        }).toThrowWithMessage(RangeError, "size must not be negative");
+    });
+});
+
 test("basic functionality", () => {
     expect(Set.prototype.isSupersetOf).toHaveLength(1);
 
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.symmetricDifference.js b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.symmetricDifference.js
index ef54b70b86..0d5f9f3408 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.symmetricDifference.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.symmetricDifference.js
@@ -1,3 +1,11 @@
+describe("errors", () => {
+    test("called with negative size", () => {
+        expect(() => {
+            new Set().symmetricDifference({ size: -1 });
+        }).toThrowWithMessage(RangeError, "size must not be negative");
+    });
+});
+
 test("basic functionality", () => {
     expect(Set.prototype.symmetricDifference).toHaveLength(1);
 
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.union.js b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.union.js
index d0469bcfb7..774be482ec 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.union.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Set/Set.prototype.union.js
@@ -1,3 +1,11 @@
+describe("errors", () => {
+    test("called with negative size", () => {
+        expect(() => {
+            new Set().union({ size: -1 });
+        }).toThrowWithMessage(RangeError, "size must not be negative");
+    });
+});
+
 test("basic functionality", () => {
     expect(Set.prototype.union).toHaveLength(1);