diff --git a/ext/gd/libgd/gd.c b/ext/gd/libgd/gd.c
index 5c7b5ce1ba6..afa7e58f336 100644
--- a/ext/gd/libgd/gd.c
+++ b/ext/gd/libgd/gd.c
@@ -2715,6 +2715,19 @@ void gdImageFilledPolygon (gdImagePtr im, gdPointPtr p, int n, int c)
 			maxy = p[i].y;
 		}
 	}
+	/* necessary special case: horizontal line */
+	if (n > 1 && miny == maxy) {
+		x1 = x2 = p[0].x;
+		for (i = 1; (i < n); i++) {
+			if (p[i].x < x1) {
+				x1 = p[i].x;
+			} else if (p[i].x > x2) {
+				x2 = p[i].x;
+			}
+		}
+		gdImageLine(im, x1, miny, x2, miny, c);
+		return;
+	}
 	pmaxy = maxy;
 	/* 2.0.16: Optimization by Ilia Chipitsine -- don't waste time offscreen */
 	if (miny < 0) {
diff --git a/ext/gd/tests/bug64641.phpt b/ext/gd/tests/bug64641.phpt
new file mode 100644
index 00000000000..d8dae9a4d36
--- /dev/null
+++ b/ext/gd/tests/bug64641.phpt
@@ -0,0 +1,38 @@
+--TEST--
+Bug #64641 (imagefilledpolygon doesn't draw horizontal line)
+--SKIPIF--
+<?php
+if (!extension_loaded('gd')) die("skip gd extension not available\n");
+?>
+--FILE--
+<?php
+require_once __DIR__ . '/similarity.inc';
+
+$im = imagecreatetruecolor(640, 480);
+
+$points = array(
+	100, 100,
+	100, 200,
+	100, 300
+);
+imagefilledpolygon($im, $points, 3, 0xFFFF00);
+
+$points = array(
+	300, 200,
+	400, 200,
+	500, 200
+);
+imagefilledpolygon($im, $points, 3, 0xFFFF00);
+
+$ex = imagecreatefrompng(__DIR__ . '/bug64641.png');
+if (($diss = calc_image_dissimilarity($ex, $im)) < 1e-5) {
+	echo "IDENTICAL";
+} else {
+	echo "DISSIMILARITY: $diss";
+}
+imagedestroy($ex);
+
+imagedestroy($im);
+?>
+--EXPECT--
+IDENTICAL
diff --git a/ext/gd/tests/bug64641.png b/ext/gd/tests/bug64641.png
new file mode 100644
index 00000000000..8376262d2f5
Binary files /dev/null and b/ext/gd/tests/bug64641.png differ
diff --git a/ext/gd/tests/imagecolorallocatealpha_basic.phpt b/ext/gd/tests/imagecolorallocatealpha_basic.phpt
index 720c50098a9..bdc417387fe 100644
--- a/ext/gd/tests/imagecolorallocatealpha_basic.phpt
+++ b/ext/gd/tests/imagecolorallocatealpha_basic.phpt
@@ -26,5 +26,5 @@ var_dump(md5(base64_encode($imgsrc)));
 var_dump($corA);
 ?>
 --EXPECT--
-string(32) "b856a0b1a15efe0f79551ebbb5651fe8"
+string(32) "2a6424e4cb4e1b7391dfff74bf136bde"
 int(842163455)
\ No newline at end of file
diff --git a/ext/gd/tests/imagefilledarc_basic.phpt b/ext/gd/tests/imagefilledarc_basic.phpt
index 9ff9bd37168..3357dd75aad 100644
--- a/ext/gd/tests/imagefilledarc_basic.phpt
+++ b/ext/gd/tests/imagefilledarc_basic.phpt
@@ -25,4 +25,4 @@ ob_end_clean();
 echo md5(base64_encode($img));
 ?>
 --EXPECT--
-894f394c7f2e2364642ef27fea6bfc33
+beffeaf5231adaaff1f21a2108fb6f7e
diff --git a/ext/gd/tests/imagefilledarc_variation1.phpt b/ext/gd/tests/imagefilledarc_variation1.phpt
index 2dec1ead2cb..2254b0910ff 100644
--- a/ext/gd/tests/imagefilledarc_variation1.phpt
+++ b/ext/gd/tests/imagefilledarc_variation1.phpt
@@ -25,4 +25,4 @@ ob_end_clean();
 echo md5(base64_encode($img));
 ?>
 --EXPECT--
-b77bbb8207e5adbebfcc8bd1c4074305
+b467492b806001c3720b3f18cfbde5b0
diff --git a/ext/gd/tests/imagefilledarc_variation2.phpt b/ext/gd/tests/imagefilledarc_variation2.phpt
index 5c8ffba0014..57686ab64ce 100644
--- a/ext/gd/tests/imagefilledarc_variation2.phpt
+++ b/ext/gd/tests/imagefilledarc_variation2.phpt
@@ -25,4 +25,4 @@ ob_end_clean();
 echo md5(base64_encode($img));
 ?>
 --EXPECT--
-b8b572812b3c85678f6c38c4ecca7619
+cfad369fc6d863785d3c95b4b4788225
diff --git a/ext/gd/tests/imagegammacorrect_basic.phpt b/ext/gd/tests/imagegammacorrect_basic.phpt
index b568728e714..33d6b1ad6c9 100644
--- a/ext/gd/tests/imagegammacorrect_basic.phpt
+++ b/ext/gd/tests/imagegammacorrect_basic.phpt
@@ -29,4 +29,4 @@ if ($gamma){
 echo md5(base64_encode($img));
 ?>
 --EXPECT--
-30639772903913594bc665743e1b9ab8
+e79553115df689ea5df18a4636380569
diff --git a/ext/gd/tests/imagegammacorrect_variation1.phpt b/ext/gd/tests/imagegammacorrect_variation1.phpt
index cda96c62876..7a321f89d87 100644
--- a/ext/gd/tests/imagegammacorrect_variation1.phpt
+++ b/ext/gd/tests/imagegammacorrect_variation1.phpt
@@ -29,4 +29,4 @@ if ($gamma){
 echo md5(base64_encode($img));
 ?>
 --EXPECT--
-7716c0905ae08bd84b4d6cba8969a42e
+b017b1ddc8bda00e82aa8cbfb54c35d4
diff --git a/ext/gd/tests/imagetruecolortopalette_basic.phpt b/ext/gd/tests/imagetruecolortopalette_basic.phpt
index b0a0394b55c..3bd0d3102e1 100644
--- a/ext/gd/tests/imagetruecolortopalette_basic.phpt
+++ b/ext/gd/tests/imagetruecolortopalette_basic.phpt
@@ -28,4 +28,4 @@ echo md5(base64_encode($img));
 ?>
 --EXPECT--
 bool(true)
-0843f63ab2f9fddedd69b0b421686bc5
\ No newline at end of file
+1d41787ff70aa0c7eea5ee9304afa36b
\ No newline at end of file