diff --git a/NEWS b/NEWS
index b27f23027e9..df7bc70af79 100644
--- a/NEWS
+++ b/NEWS
@@ -25,6 +25,8 @@ PHP                                                                        NEWS
     falling back to IMG_CROP_SIDES.
   . The default $mode parameter of imagecropauto() has been changed to
     IMG_CROP_DEFAULT; passing -1 is now deprecated.
+  . Added support for aspect ratio preserving scaling to a fixed height for
+    imagescale(). (Andreas Treichel)
 
 - Hash:
   . The hash extension is now an integral part of PHP and cannot be disabled
diff --git a/UPGRADING b/UPGRADING
index ce157fc702d..2da9ad242b9 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -145,6 +145,8 @@ PHP 7.4 UPGRADE NOTES
      * Threshold-cropping now uses the algorithm of system libgd
   . The default $mode parameter of imagecropauto() has been changed to
     IMG_CROP_DEFAULT; passing -1 is now deprecated.
+  . imagescale() now supports aspect ratio preserving scaling to a fixed height
+    by passing -1 as $new_width.
 
 - Hash:
   . The hash extension cannot be disabled anymore and is always an integral
diff --git a/ext/gd/gd.c b/ext/gd/gd.c
index f4b7d2c2a5b..d4e4db1be6b 100644
--- a/ext/gd/gd.c
+++ b/ext/gd/gd.c
@@ -4757,15 +4757,19 @@ PHP_FUNCTION(imagescale)
 		RETURN_FALSE;
 	}
 
-	if (tmp_h < 0) {
+	if (tmp_h < 0 || tmp_w < 0) {
 		/* preserve ratio */
 		long src_x, src_y;
 
 		src_x = gdImageSX(im);
 		src_y = gdImageSY(im);
-		if (src_x) {
+
+		if (src_x && tmp_h < 0) {
 			tmp_h = tmp_w * src_y / src_x;
 		}
+		if (src_y && tmp_w < 0) {
+			tmp_w = tmp_h * src_x / src_y;
+		}
 	}
 
 	if (tmp_h <= 0 || tmp_h > INT_MAX || tmp_w <= 0 || tmp_w > INT_MAX) {
diff --git a/ext/gd/tests/imagescale_preserve_ratio.phpt b/ext/gd/tests/imagescale_preserve_ratio.phpt
new file mode 100644
index 00000000000..00076e431e5
--- /dev/null
+++ b/ext/gd/tests/imagescale_preserve_ratio.phpt
@@ -0,0 +1,55 @@
+--TEST--
+Scale images and preserve aspect ratio
+--SKIPIF--
+<?php
+if (!extension_loaded('gd')) die("skip gd extension not available\n");
+?>
+--FILE--
+<?php
+
+$img = imagecreatetruecolor ( 256, 384);
+
+$thumbnail = imagescale($img, 64, -1, IMG_BICUBIC);
+var_dump(imagesx($thumbnail));
+var_dump(imagesy($thumbnail));
+
+$thumbnail = imagescale($img, -1, 64, IMG_BICUBIC);
+var_dump(imagesx($thumbnail));
+var_dump(imagesy($thumbnail));
+
+$img = imagecreatetruecolor ( 384, 256);
+
+$thumbnail = imagescale($img, 64, -1, IMG_BICUBIC);
+var_dump(imagesx($thumbnail));
+var_dump(imagesy($thumbnail));
+
+$thumbnail = imagescale($img, -1, 64, IMG_BICUBIC);
+var_dump(imagesx($thumbnail));
+var_dump(imagesy($thumbnail));
+
+$img = imagecreatetruecolor ( 256, 256);
+
+$thumbnail = imagescale($img, 64, -1, IMG_BICUBIC);
+var_dump(imagesx($thumbnail));
+var_dump(imagesy($thumbnail));
+
+$thumbnail = imagescale($img, -1, 64, IMG_BICUBIC);
+var_dump(imagesx($thumbnail));
+var_dump(imagesy($thumbnail));
+
+?>
+DONE
+--EXPECT--
+int(64)
+int(96)
+int(42)
+int(64)
+int(64)
+int(42)
+int(96)
+int(64)
+int(64)
+int(64)
+int(64)
+int(64)
+DONE