diff --git a/src/server/services/wms/qgswmsrendercontext.cpp b/src/server/services/wms/qgswmsrendercontext.cpp
index de8e976501b..eed87e272b6 100644
--- a/src/server/services/wms/qgswmsrendercontext.cpp
+++ b/src/server/services/wms/qgswmsrendercontext.cpp
@@ -650,6 +650,9 @@ bool QgsWmsRenderContext::isValidWidthHeight() const
 
 bool QgsWmsRenderContext::isValidWidthHeight( int width, int height ) const
 {
+  if ( width <= 0 || height <= 0 )
+    return false;
+
   //test if maxWidth / maxHeight are set in the project or as an env variable
   //and WIDTH / HEIGHT parameter is in the range allowed range
   //WIDTH
@@ -692,14 +695,15 @@ bool QgsWmsRenderContext::isValidWidthHeight( int width, int height ) const
     return false;
   }
 
-  // Sanity check from internal QImage checks (see qimage.cpp)
+  // Sanity check from internal QImage checks
+  // (see QImageData::calculateImageParameters() in qimage_p.h)
   // this is to report a meaningful error message in case of
   // image creation failure and to differentiate it from out
   // of memory conditions.
 
   // depth for now it cannot be anything other than 32, but I don't like
   // to hardcode it: I hope we will support other depths in the future.
-  uint depth = 32;
+  int depth = 32;
   switch ( mParameters.format() )
   {
     case QgsWmsParameters::Format::JPG:
@@ -708,12 +712,12 @@ bool QgsWmsRenderContext::isValidWidthHeight( int width, int height ) const
       depth = 32;
   }
 
+  if ( width > ( std::numeric_limits<int>::max() - 31 ) / depth )
+    return false;
+
   const int bytes_per_line = ( ( width * depth + 31 ) >> 5 ) << 2; // bytes per scanline (must be multiple of 4)
 
-  if ( std::numeric_limits<int>::max() / depth < static_cast<uint>( width )
-       || bytes_per_line <= 0
-       || height <= 0
-       || std::numeric_limits<int>::max() / static_cast<uint>( bytes_per_line ) < static_cast<uint>( height )
+  if ( std::numeric_limits<int>::max() / bytes_per_line < height
        || std::numeric_limits<int>::max() / sizeof( uchar * ) < static_cast<uint>( height ) )
   {
     return false;
diff --git a/tests/src/python/test_qgsserver_wms_getmap.py b/tests/src/python/test_qgsserver_wms_getmap.py
index 7b05351e7c4..e2b58c08385 100644
--- a/tests/src/python/test_qgsserver_wms_getmap.py
+++ b/tests/src/python/test_qgsserver_wms_getmap.py
@@ -336,6 +336,25 @@ class TestQgsServerWMSGetMap(QgsServerTestBase):
         err = b"HEIGHT (\'FOO\') cannot be converted into int" in r
         self.assertTrue(err)
 
+        # height should be > 0
+        qs = "?" + "&".join(["%s=%s" % i for i in list({
+            "MAP": urllib.parse.quote(self.projectPath),
+            "SERVICE": "WMS",
+            "VERSION": "1.1.1",
+            "REQUEST": "GetMap",
+            "LAYERS": "Country",
+            "STYLES": "",
+            "FORMAT": "image/png",
+            "BBOX": "-16817707,-4710778,5696513,14587125",
+            "HEIGHT": "-1",
+            "WIDTH": "1",
+            "CRS": "EPSG:3857"
+        }.items())])
+
+        r, h = self._result(self._execute_request(qs))
+        err = b"The requested map size is too large" in r
+        self.assertTrue(err)
+
         # width should be an int
         qs = "?" + "&".join(["%s=%s" % i for i in list({
             "MAP": urllib.parse.quote(self.projectPath),
@@ -355,6 +374,25 @@ class TestQgsServerWMSGetMap(QgsServerTestBase):
         err = b"WIDTH (\'FOO\') cannot be converted into int" in r
         self.assertTrue(err)
 
+        # width should be > 0
+        qs = "?" + "&".join(["%s=%s" % i for i in list({
+            "MAP": urllib.parse.quote(self.projectPath),
+            "SERVICE": "WMS",
+            "VERSION": "1.1.1",
+            "REQUEST": "GetMap",
+            "LAYERS": "Country",
+            "STYLES": "",
+            "FORMAT": "image/png",
+            "BBOX": "-16817707,-4710778,5696513,14587125",
+            "HEIGHT": "1",
+            "WIDTH": "-1",
+            "CRS": "EPSG:3857"
+        }.items())])
+
+        r, h = self._result(self._execute_request(qs))
+        err = b"The requested map size is too large" in r
+        self.assertTrue(err)
+
         # bbox should be formatted like "double,double,double,double"
         qs = "?" + "&".join(["%s=%s" % i for i in list({
             "MAP": urllib.parse.quote(self.projectPath),