diff --git a/NEWS b/NEWS
index 9d6235205b0..411f81e4b5e 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,10 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? 2016, PHP 7.1.0RC1
 
+-GD:
+  . Fixed bug #66005 (imagecopy does not support 1bit transparency on truecolor
+    images). (cmb)
+
 - Reflection:
   . Reverted prepending \ for class names and ? for nullable types returned
     from ReflectionType::__toString(). (Trowski)
diff --git a/ext/gd/libgd/gd.c b/ext/gd/libgd/gd.c
index 51258d484f4..3ad51ada4bb 100644
--- a/ext/gd/libgd/gd.c
+++ b/ext/gd/libgd/gd.c
@@ -2245,7 +2245,9 @@ void gdImageCopy (gdImagePtr dst, gdImagePtr src, int dstX, int dstY, int srcX,
 			for (y = 0; (y < h); y++) {
 				for (x = 0; (x < w); x++) {
 					int c = gdImageGetTrueColorPixel (src, srcX + x, srcY + y);
-					gdImageSetPixel (dst, dstX + x, dstY + y, c);
+					if (c != src->transparent) {
+						gdImageSetPixel (dst, dstX + x, dstY + y, c);
+					}
 				}
 			}
 		} else {
diff --git a/ext/gd/tests/bug66005.phpt b/ext/gd/tests/bug66005.phpt
new file mode 100644
index 00000000000..a01c5c32b85
--- /dev/null
+++ b/ext/gd/tests/bug66005.phpt
@@ -0,0 +1,35 @@
+--TEST--
+Bug #66005 (imagecopy does not support 1bit transparency on truecolor images)
+--SKIPIF--
+<?php
+if (!extension_loaded('gd')) die('skip gd extension not available');
+?>
+--FILE--
+<?php
+$dest = imagecreatetruecolor(150, 50);
+$transparent = imagecolorallocatealpha($dest, 255, 255, 255, 127);
+imagealphablending($dest, false);
+imagefill($dest, 1, 1, $transparent);
+imagesavealpha($dest, true);
+
+// Palette image with transparent color
+$png_palette = imagecreatefromstring(base64_decode('iVBORw0KGgoAAAANSUhEUgAAADIAAAAyAgMAAABjUWAiAAAACVBMVEUAAAD/AAD///9nGWQeAAAAAXRSTlMAQObYZgAAAEFJREFUKM9jYBimIASZIxoagOAwhoaGInisQJ4DksJQJKWoPCAnNIQYHsgChBX4eMSbiddlqH5A9R+q39HCZWgDAFxFGyOrmguhAAAAAElFTkSuQmCCPHP'));
+
+// 24 bit with transparent color
+$png_24 = imagecreatefromstring(base64_decode('iVBORw0KGgoAAAANSUhEUgAAADIAAAAyCAIAAACRXR/mAAAABnRSTlMAAAAAAABupgeRAAAAVklEQVRYw+3UQQqAMBAEwf3/p9eTBxEPiWAmWMU8oGFJqgAAuOpzWTX3xQUti+uRJTZ9V5aY1bOTFZLV7yZr9zt6ibv/qPXfrMpsGipbIy7oqQ8AYJED1plDy5PCu2sAAAAASUVORK5CYII='));
+
+// 32 bit with full alpha channel
+$png_full = imagecreatefromstring(base64_decode('iVBORw0KGgoAAAANSUhEUgAAADIAAAAyCAYAAAAeP4ixAAAAXklEQVRo3u3XMQrAIBBFwb3/pU2VwiJNIvjdzMD2PlBwqwAAAGajatxz9OGf5viA+KA3EXExXyKiYlqErIiIiBGSFLIyYmuMkO7Xy2MX4ovS/ONoH7Eh/m1nBwCASBe3VYeVaAy8PwAAAABJRU5ErkJggg=='));
+
+imagecopy($dest, $png_palette, 0, 0, 0, 0, 50, 50);
+imagecopy($dest, $png_24, 50, 0, 0, 0, 50, 50);
+imagecopy($dest, $png_full, 100, 0, 0, 0, 50, 50);
+
+ob_start();
+imagegd($dest);
+echo md5(ob_get_clean()), PHP_EOL;
+?>
+==DONE==
+--EXPECT--
+9b36049de01006b367efd433f1689043
+==DONE==