diff --git a/src/Analyser/MutatingScope.php b/src/Analyser/MutatingScope.php
index 42034f0ae3..77a265078a 100644
--- a/src/Analyser/MutatingScope.php
+++ b/src/Analyser/MutatingScope.php
@@ -4498,7 +4498,7 @@ public function addTypeToExpression(Expr $expr, Type $type): self
 
 		if ($originalExprType->equals($nativeType)) {
 			$newType = TypeCombinator::intersect($type, $originalExprType);
-			if ($newType->isConstantScalarValue()->yes() && $newType->equals($originalExprType)) {
+			if ($newType->isObject()->no() && $newType->equals($originalExprType)) {
 				// don't add the same type over and over again to improve performance
 				return $this;
 			}
diff --git a/src/Type/MixedType.php b/src/Type/MixedType.php
index 487a474827..175762d000 100644
--- a/src/Type/MixedType.php
+++ b/src/Type/MixedType.php
@@ -314,6 +314,10 @@ public function equals(Type $type): bool
 			return false;
 		}
 
+		if ($type instanceof ErrorType) {
+			return false;
+		}
+
 		if ($this->subtractedType === null) {
 			if ($type->subtractedType === null) {
 				return true;
diff --git a/tests/PHPStan/Type/MixedTypeTest.php b/tests/PHPStan/Type/MixedTypeTest.php
index 3ffc8f9db7..85edf6bc4f 100644
--- a/tests/PHPStan/Type/MixedTypeTest.php
+++ b/tests/PHPStan/Type/MixedTypeTest.php
@@ -1164,4 +1164,50 @@ public function testSubtractedHasOffsetValueType(MixedType $mixedType, Type $typ
 		);
 	}
 
+	/** @dataProvider dataEquals */
+	public function testEquals(MixedType $mixedType, Type $typeToCompare, bool $expectedResult): void
+	{
+		$this->assertSame(
+			$expectedResult,
+			$mixedType->equals($typeToCompare),
+			sprintf('%s -> equals(%s)', $mixedType->describe(VerbosityLevel::precise()), $typeToCompare->describe(VerbosityLevel::precise())),
+		);
+	}
+
+	public function dataEquals(): array
+	{
+		return [
+			[
+				new MixedType(),
+				new MixedType(),
+				true,
+			],
+			[
+				new MixedType(true),
+				new MixedType(),
+				true,
+			],
+			[
+				new MixedType(),
+				new MixedType(true),
+				true,
+			],
+			[
+				new MixedType(),
+				new MixedType(true, new IntegerType()),
+				false,
+			],
+			[
+				new MixedType(),
+				new ErrorType(),
+				false,
+			],
+			[
+				new MixedType(true),
+				new ErrorType(),
+				false,
+			],
+		];
+	}
+
 }