diff --git a/lib/gdlib.php b/lib/gdlib.php
index bd69ece35fa..cd35b37c610 100644
--- a/lib/gdlib.php
+++ b/lib/gdlib.php
@@ -359,8 +359,8 @@ function resize_image_from_image($original, $imageinfo, $width, $height, $forcec
     }
 
     if ($ratio < 1) {
-        $targetwidth    = floor($originalwidth * $ratio);
-        $targetheight   = floor($originalheight * $ratio);
+        $targetwidth    = round($originalwidth * $ratio);
+        $targetheight   = round($originalheight * $ratio);
     } else {
         // Do not enlarge the original file if it is smaller than the requested thumbnail size.
         $targetwidth    = $originalwidth;
diff --git a/lib/tests/gdlib_test.php b/lib/tests/gdlib_test.php
index d322d33d5cf..f0401f974e1 100644
--- a/lib/tests/gdlib_test.php
+++ b/lib/tests/gdlib_test.php
@@ -87,7 +87,7 @@ class gdlib_test extends \basic_testcase {
         $newpng = resize_image($pngpath, null, 24);
         $this->assertTrue(is_string($newpng));
         $imageinfo = getimagesizefromstring($newpng);
-        $this->assertEquals(89, $imageinfo[0]);
+        $this->assertEquals(90, $imageinfo[0]);
         $this->assertEquals(24, $imageinfo[1]);
         $this->assertEquals('image/png', $imageinfo['mime']);
 
@@ -96,7 +96,7 @@ class gdlib_test extends \basic_testcase {
         $this->assertTrue(is_string($newpng));
         $imageinfo = getimagesizefromstring($newpng);
         $this->assertEquals(100, $imageinfo[0]);
-        $this->assertEquals(26, $imageinfo[1]);
+        $this->assertEquals(27, $imageinfo[1]);
         $this->assertEquals('image/png', $imageinfo['mime']);
 
         // Preferred width and height.
@@ -121,7 +121,7 @@ class gdlib_test extends \basic_testcase {
         $newpng = resize_image_from_image($imageresource, $origimageinfo, null, 24);
         $this->assertTrue(is_string($newpng));
         $imageinfo = getimagesizefromstring($newpng);
-        $this->assertEquals(89, $imageinfo[0]);
+        $this->assertEquals(90, $imageinfo[0]);
         $this->assertEquals(24, $imageinfo[1]);
         $this->assertEquals('image/png', $imageinfo['mime']);
 
@@ -131,7 +131,7 @@ class gdlib_test extends \basic_testcase {
         $this->assertTrue(is_string($newpng));
         $imageinfo = getimagesizefromstring($newpng);
         $this->assertEquals(100, $imageinfo[0]);
-        $this->assertEquals(26, $imageinfo[1]);
+        $this->assertEquals(27, $imageinfo[1]);
         $this->assertEquals('image/png', $imageinfo['mime']);
 
         // Preferred width and height.