diff --git a/src/Type/Php/DateTimeCreateDynamicReturnTypeExtension.php b/src/Type/Php/DateTimeCreateDynamicReturnTypeExtension.php
index 26f726c9716..bd00c0f12aa 100644
--- a/src/Type/Php/DateTimeCreateDynamicReturnTypeExtension.php
+++ b/src/Type/Php/DateTimeCreateDynamicReturnTypeExtension.php
@@ -8,10 +8,10 @@
 use PHPStan\Analyser\Scope;
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Type\Constant\ConstantBooleanType;
-use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\DynamicFunctionReturnTypeExtension;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
 use function count;
 use function date_create;
 use function in_array;
@@ -30,16 +30,20 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 			return null;
 		}
 
-		$datetime = $scope->getType($functionCall->getArgs()[0]->value);
+		$datetimes = $scope->getType($functionCall->getArgs()[0]->value)->getConstantStrings();
 
-		if (!$datetime instanceof ConstantStringType) {
+		if (count($datetimes) === 0) {
 			return null;
 		}
 
-		$isValid = date_create($datetime->getValue()) !== false;
-
+		$types = [];
 		$className = $functionReflection->getName() === 'date_create' ? DateTime::class : DateTimeImmutable::class;
-		return $isValid ? new ObjectType($className) : new ConstantBooleanType(false);
+		foreach ($datetimes as $constantString) {
+			$isValid = date_create($constantString->getValue()) !== false;
+			$types[] = $isValid ? new ObjectType($className) : new ConstantBooleanType(false);
+		}
+
+		return TypeCombinator::union(...$types);
 	}
 
 }
diff --git a/src/Type/Php/DateTimeDynamicReturnTypeExtension.php b/src/Type/Php/DateTimeDynamicReturnTypeExtension.php
index 22945f9966c..b18c8534dfc 100644
--- a/src/Type/Php/DateTimeDynamicReturnTypeExtension.php
+++ b/src/Type/Php/DateTimeDynamicReturnTypeExtension.php
@@ -7,12 +7,11 @@
 use PhpParser\Node\Expr\FuncCall;
 use PHPStan\Analyser\Scope;
 use PHPStan\Reflection\FunctionReflection;
-use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\Type\Constant\ConstantBooleanType;
-use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\DynamicFunctionReturnTypeExtension;
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
 use function count;
 use function in_array;
 
@@ -24,25 +23,29 @@ public function isFunctionSupported(FunctionReflection $functionReflection): boo
 		return in_array($functionReflection->getName(), ['date_create_from_format', 'date_create_immutable_from_format'], true);
 	}
 
-	public function getTypeFromFunctionCall(FunctionReflection $functionReflection, FuncCall $functionCall, Scope $scope): Type
+	public function getTypeFromFunctionCall(FunctionReflection $functionReflection, FuncCall $functionCall, Scope $scope): ?Type
 	{
-		$defaultReturnType = ParametersAcceptorSelector::selectSingle($functionReflection->getVariants())->getReturnType();
-
 		if (count($functionCall->getArgs()) < 2) {
-			return $defaultReturnType;
+			return null;
 		}
 
-		$format = $scope->getType($functionCall->getArgs()[0]->value);
-		$datetime = $scope->getType($functionCall->getArgs()[1]->value);
+		$formats = $scope->getType($functionCall->getArgs()[0]->value)->getConstantStrings();
+		$datetimes = $scope->getType($functionCall->getArgs()[1]->value)->getConstantStrings();
 
-		if (!$format instanceof ConstantStringType || !$datetime instanceof ConstantStringType) {
-			return $defaultReturnType;
+		if (count($formats) === 0 || count($datetimes) === 0) {
+			return null;
 		}
 
-		$isValid = (DateTime::createFromFormat($format->getValue(), $datetime->getValue()) !== false);
-
+		$types = [];
 		$className = $functionReflection->getName() === 'date_create_from_format' ? DateTime::class : DateTimeImmutable::class;
-		return $isValid ? new ObjectType($className) : new ConstantBooleanType(false);
+		foreach ($formats as $formatConstantString) {
+			foreach ($datetimes as $datetimeConstantString) {
+				$isValid = (DateTime::createFromFormat($formatConstantString->getValue(), $datetimeConstantString->getValue()) !== false);
+				$types[] = $isValid ? new ObjectType($className) : new ConstantBooleanType(false);
+			}
+		}
+
+		return TypeCombinator::union(...$types);
 	}
 
 }
diff --git a/tests/PHPStan/Analyser/data/DateTimeCreateDynamicReturnTypes.php b/tests/PHPStan/Analyser/data/DateTimeCreateDynamicReturnTypes.php
index b2b89ec1b73..f50a903dbf2 100644
--- a/tests/PHPStan/Analyser/data/DateTimeCreateDynamicReturnTypes.php
+++ b/tests/PHPStan/Analyser/data/DateTimeCreateDynamicReturnTypes.php
@@ -29,4 +29,20 @@ public function localVariables(): void {
 		assertType('DateTimeImmutable', date_create_immutable($datetime));
 	}
 
+	/**
+	 * @param '2020-04-09'|'2022-02-01' $datetimes
+	 * @param '1990-04-11'|'foo' $maybeDatetimes
+	 * @param 'foo'|'bar' $noDatetimes
+	 */
+	public function unions(string $datetimes, string $maybeDatetimes, string $noDatetimes): void {
+		assertType('DateTime', date_create($datetimes));
+		assertType('DateTimeImmutable', date_create_immutable($datetimes));
+
+		assertType('DateTime|false', date_create($maybeDatetimes));
+		assertType('DateTimeImmutable|false', date_create_immutable($maybeDatetimes));
+
+		assertType('false', date_create($noDatetimes));
+		assertType('false', date_create_immutable($noDatetimes));
+	}
+
 }
diff --git a/tests/PHPStan/Analyser/data/DateTimeDynamicReturnTypes.php b/tests/PHPStan/Analyser/data/DateTimeDynamicReturnTypes.php
index 33c853a0b11..7c92cb0879b 100644
--- a/tests/PHPStan/Analyser/data/DateTimeDynamicReturnTypes.php
+++ b/tests/PHPStan/Analyser/data/DateTimeDynamicReturnTypes.php
@@ -38,4 +38,20 @@ public function localVariables(): void {
 		assertType('DateTimeImmutable', date_create_immutable_from_format($format, $datetime));
 	}
 
+	/**
+	 * @param '2020-04-09'|'2022-02-01' $datetimes
+	 * @param '1990-04-11'|'foo' $maybeDatetimes
+	 * @param 'foo'|'bar' $noDatetimes
+	 */
+	public function unions(string $datetimes, string $maybeDatetimes, string $noDatetimes): void {
+		assertType('DateTime', date_create_from_format('Y-m-d', $datetimes));
+		assertType('DateTimeImmutable', date_create_immutable_from_format('Y-m-d', $datetimes));
+
+		assertType('DateTime|false', date_create_from_format('Y-m-d', $maybeDatetimes));
+		assertType('DateTimeImmutable|false', date_create_immutable_from_format('Y-m-d', $maybeDatetimes));
+
+		assertType('false', date_create_from_format('Y-m-d', $noDatetimes));
+		assertType('false', date_create_immutable_from_format('Y-m-d', $noDatetimes));
+	}
+
 }