diff --git a/src/Reflection/SignatureMap/functionMap.php b/src/Reflection/SignatureMap/functionMap.php
index a9d2aa7998..74cee12444 100644
--- a/src/Reflection/SignatureMap/functionMap.php
+++ b/src/Reflection/SignatureMap/functionMap.php
@@ -4536,8 +4536,7 @@
 'imagealphablending' => ['bool', 'im'=>'resource', 'on'=>'bool'],
 'imageantialias' => ['bool', 'im'=>'resource', 'on'=>'bool'],
 'imagearc' => ['bool', 'im'=>'resource', 'cx'=>'int', 'cy'=>'int', 'w'=>'int', 'h'=>'int', 's'=>'int', 'e'=>'int', 'col'=>'int'],
-'imagebmp' => ['bool', 'image'=>'resource', 'to'=>'string|resource', 'compressed='=>'bool'],
-'imagebmp\'1' => ['string|false', 'image'=>'resource', 'to='=>'null', 'compressed='=>'bool'],
+'imagebmp' => ['bool', 'image'=>'resource', 'to='=>'string|resource|null', 'compressed='=>'bool'],
 'imagechar' => ['bool', 'im'=>'resource', 'font'=>'int', 'x'=>'int', 'y'=>'int', 'c'=>'string', 'col'=>'int'],
 'imagecharup' => ['bool', 'im'=>'resource', 'font'=>'int', 'x'=>'int', 'y'=>'int', 'c'=>'string', 'col'=>'int'],
 'imagecolorallocate' => ['int', 'im'=>'resource', 'red'=>'int', 'green'=>'int', 'blue'=>'int'],
@@ -4594,18 +4593,15 @@
 'imageftbbox' => ['array', 'size'=>'float', 'angle'=>'float', 'font_file'=>'string', 'text'=>'string', 'extrainfo='=>'array'],
 'imagefttext' => ['array', 'im'=>'resource', 'size'=>'float', 'angle'=>'float', 'x'=>'int', 'y'=>'int', 'col'=>'int', 'font_file'=>'string', 'text'=>'string', 'extrainfo='=>'array'],
 'imagegammacorrect' => ['bool', 'im'=>'resource', 'inputgamma'=>'float', 'outputgamma'=>'float'],
-'imagegd' => ['bool', 'im'=>'resource', 'filename'=>'string|resource'],
-'imagegd\'1' => ['string|false', 'im'=>'resource', 'filename='=>'null'],
-'imagegd2' => ['bool', 'im'=>'resource', 'filename'=>'string|resource', 'chunk_size='=>'int', 'type='=>'int'],
-'imagegd2\'1' => ['string|false', 'im'=>'resource', 'filename='=>'null', 'chunk_size='=>'int', 'type='=>'int'],
+'imagegd' => ['bool', 'im'=>'resource', 'filename='=>'string|resource|null'],
+'imagegd2' => ['bool', 'im'=>'resource', 'filename='=>'string|resource|null', 'chunk_size='=>'int', 'type='=>'int'],
 'imagegetclip' => ['array', 'im'=>'resource'],
-'imagegif' => ['bool', 'im'=>'resource', 'filename'=>'string|resource'],
-'imagegif\'1' => ['string|false', 'im'=>'resource', 'filename='=>'null'],
+'imagegif' => ['bool', 'im'=>'resource', 'filename='=>'string|resource|null'],
 'imagegrabscreen' => ['resource'],
 'imagegrabwindow' => ['resource', 'window_handle'=>'int', 'client_area='=>'int'],
 'imageinterlace' => ['int', 'im'=>'resource', 'interlace='=>'int'],
 'imageistruecolor' => ['bool', 'im'=>'resource'],
-'imagejpeg' => ['bool', 'im'=>'resource', 'filename'=>'string|resource', 'quality='=>'int'],
+'imagejpeg' => ['bool', 'im'=>'resource', 'filename='=>'string|resource|null', 'quality='=>'int'],
 'imagejpeg\'1' => ['string|false', 'im'=>'resource', 'filename='=>'null', 'quality='=>'int'],
 'imagelayereffect' => ['bool', 'im'=>'resource', 'effect'=>'int'],
 'imageline' => ['bool', 'im'=>'resource', 'x1'=>'int', 'y1'=>'int', 'x2'=>'int', 'y2'=>'int', 'col'=>'int'],
@@ -4616,8 +4612,7 @@
 'imageopenpolygon' => ['bool', 'image'=>'resource', 'points'=>'array', 'num_points'=>'int', 'color'=>'int'],
 'imagepalettecopy' => ['void', 'dst'=>'resource', 'src'=>'resource'],
 'imagepalettetotruecolor' => ['bool', 'src'=>'resource'],
-'imagepng' => ['bool', 'im'=>'resource', 'filename'=>'string|resource', 'quality='=>'int', 'filters='=>'int'],
-'imagepng\'1' => ['string|false', 'im'=>'resource', 'filename='=>'null', 'quality='=>'int', 'filters='=>'int'],
+'imagepng' => ['bool', 'im'=>'resource', 'filename='=>'string|resource|null', 'quality='=>'int', 'filters='=>'int'],
 'imagepolygon' => ['bool', 'im'=>'resource', 'point'=>'array', 'num_points'=>'int', 'col'=>'int'],
 'imagepsbbox' => ['array', 'text'=>'string', 'font'=>'', 'size'=>'int', 'space'=>'int', 'tightness'=>'int', 'angle'=>'float'],
 'imagepsencodefont' => ['bool', 'font_index'=>'resource', 'encodingfile'=>'string'],
@@ -4646,12 +4641,9 @@
 'imagettfbbox' => ['array', 'size'=>'float', 'angle'=>'float', 'font_file'=>'string', 'text'=>'string'],
 'imagettftext' => ['array', 'im'=>'resource', 'size'=>'float', 'angle'=>'float', 'x'=>'int', 'y'=>'int', 'col'=>'int', 'font_file'=>'string', 'text'=>'string'],
 'imagetypes' => ['int'],
-'imagewbmp' => ['bool', 'im'=>'resource', 'filename'=>'string|resource', 'foreground='=>'int'],
-'imagewbmp\'1' => ['string|false', 'im'=>'resource', 'filename='=>'null', 'foreground='=>'int'],
-'imagewebp' => ['bool', 'im'=>'resource', 'filename'=>'string|resource', 'quality='=>'int'],
-'imagewebp\'1' => ['string|false', 'im'=>'resource', 'filename='=>'null', 'quality='=>'int'],
-'imagexbm' => ['bool', 'im'=>'resource', 'filename'=>'string|resource', 'foreground='=>'int'],
-'imagexbm\'1' => ['string|false', 'im'=>'resource', 'filename='=>'null', 'foreground='=>'int'],
+'imagewbmp' => ['bool', 'im'=>'resource', 'filename='=>'string|resource|null', 'foreground='=>'int'],
+'imagewebp' => ['bool', 'im'=>'resource', 'filename='=>'string|resource|null', 'quality='=>'int'],
+'imagexbm' => ['bool', 'im'=>'resource', 'filename='=>'string|resource|null', 'foreground='=>'int'],
 'Imagick::__construct' => ['void', 'files='=>''],
 'Imagick::__toString' => ['string'],
 'Imagick::adaptiveBlurImage' => ['bool', 'radius'=>'float', 'sigma'=>'float', 'channel='=>'int'],
diff --git a/tests/PHPStan/Analyser/data/graphics-draw-return-types.php b/tests/PHPStan/Analyser/data/graphics-draw-return-types.php
index 59c91184f3..6b4b4d77a0 100644
--- a/tests/PHPStan/Analyser/data/graphics-draw-return-types.php
+++ b/tests/PHPStan/Analyser/data/graphics-draw-return-types.php
@@ -5,7 +5,7 @@
 $image = imagecreatetruecolor(1, 1);
 $memoryHandle = fopen('php://memory', 'w');
 
-assertType('string|false', imagegd($image));
-assertType('string|false', imagegd($image, null));
+assertType('bool', imagegd($image));
+assertType('bool', imagegd($image, null));
 assertType('bool', imagegd($image, 'php://memory'));
 assertType('bool', imagegd($image, $memoryHandle));