diff --git a/Userland/Libraries/LibJS/Runtime/ErrorTypes.h b/Userland/Libraries/LibJS/Runtime/ErrorTypes.h
index db65922626..af2b0a9d79 100644
--- a/Userland/Libraries/LibJS/Runtime/ErrorTypes.h
+++ b/Userland/Libraries/LibJS/Runtime/ErrorTypes.h
@@ -54,7 +54,6 @@
     M(NotASymbol, "{} is not a symbol")                                                                                                 \
     M(NotIterable, "{} is not iterable")                                                                                                \
     M(NotObjectCoercible, "{} cannot be converted to an object")                                                                        \
-    M(NumberIncompatibleThis, "Number.prototype.{}() called with incompatible this target")                                             \
     M(ObjectDefinePropertyReturnedFalse, "Object's [[DefineProperty]] method returned false")                                           \
     M(ObjectFreezeFailed, "Could not freeze object")                                                                                    \
     M(ObjectSealFailed, "Could not seal object")                                                                                        \
diff --git a/Userland/Libraries/LibJS/Runtime/NumberPrototype.cpp b/Userland/Libraries/LibJS/Runtime/NumberPrototype.cpp
index 568275dee4..fcf42d8721 100644
--- a/Userland/Libraries/LibJS/Runtime/NumberPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/NumberPrototype.cpp
@@ -42,22 +42,21 @@ NumberPrototype::~NumberPrototype()
 {
 }
 
-// https://tc39.es/ecma262/#thisnumbervalue
-static Value this_number_value(GlobalObject& global_object, StringView const& name)
+// thisNumberValue, https://tc39.es/ecma262/#thisnumbervalue
+static Value this_number_value(GlobalObject& global_object, Value value)
 {
+    if (value.is_number())
+        return value;
+    if (value.is_object() && is<NumberObject>(value.as_object()))
+        return static_cast<NumberObject&>(value.as_object()).value_of();
     auto& vm = global_object.vm();
-    auto this_value = vm.this_value(global_object);
-    if (this_value.is_number())
-        return this_value;
-    if (this_value.is_object() && is<NumberObject>(this_value.as_object()))
-        return static_cast<NumberObject&>(this_value.as_object()).value_of();
-    vm.throw_exception<TypeError>(global_object, ErrorType::NumberIncompatibleThis, name);
+    vm.throw_exception<TypeError>(global_object, ErrorType::NotA, "Number");
     return {};
 }
 
 JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_string)
 {
-    auto number_value = this_number_value(global_object, "toString");
+    auto number_value = this_number_value(global_object, vm.this_value(global_object));
     if (vm.exception())
         return {};
 
@@ -134,7 +133,7 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_string)
 
 JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::value_of)
 {
-    return this_number_value(global_object, "valueOf");
+    return this_number_value(global_object, vm.this_value(global_object));
 }
 
 }
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Number/Number.prototype.toString.js b/Userland/Libraries/LibJS/Tests/builtins/Number/Number.prototype.toString.js
index da478dcf08..7ebc4fb748 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Number/Number.prototype.toString.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Number/Number.prototype.toString.js
@@ -77,7 +77,7 @@ test("errors", () => {
         [true, [], {}, Symbol("foo"), "bar", 1n].forEach(value => {
             expect(() => Number.prototype.toString.call(value)).toThrowWithMessage(
                 TypeError,
-                "Number.prototype.toString() called with incompatible this target"
+                "Not a Number object"
             );
         });
     });
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Number/Number.prototype.valueOf.js b/Userland/Libraries/LibJS/Tests/builtins/Number/Number.prototype.valueOf.js
index eb9cae2c59..7871a1ed43 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/Number/Number.prototype.valueOf.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/Number/Number.prototype.valueOf.js
@@ -14,7 +14,7 @@ test("errors", () => {
         [true, [], {}, Symbol("foo"), "bar", 1n].forEach(value => {
             expect(() => Number.prototype.valueOf.call(value)).toThrowWithMessage(
                 TypeError,
-                "Number.prototype.valueOf() called with incompatible this target"
+                "Not a Number object"
             );
         });
     });