diff --git a/nova/tests/unit/virt/test_hardware.py b/nova/tests/unit/virt/test_hardware.py
index eb015d735669..9201177fe27c 100644
--- a/nova/tests/unit/virt/test_hardware.py
+++ b/nova/tests/unit/virt/test_hardware.py
@@ -2429,15 +2429,23 @@ class VirtMemoryPagesTestCase(test.NoDBTestCase):
                 spec={"hw:mem_page_size": "2048"}))
 
     def test_get_requested_mempages_pagesize_from_flavor_invalid(self):
-        self.assertRaises(
+        ex = self.assertRaises(
             exception.MemoryPageSizeInvalid,
             self._test_get_requested_mempages_pagesize,
             {"hw:mem_page_size": "foo"})
+        self.assertIn("foo", str(ex))
 
-        self.assertRaises(
+        ex = self.assertRaises(
             exception.MemoryPageSizeInvalid,
             self._test_get_requested_mempages_pagesize,
             {"hw:mem_page_size": "-42"})
+        self.assertIn("-42", str(ex))
+
+        ex = self.assertRaises(
+            exception.MemoryPageSizeInvalid,
+            self._test_get_requested_mempages_pagesize,
+            {"hw:mem_page_size": "2M"})
+        self.assertIn("2M", str(ex))
 
     def test_get_requested_mempages_pagesizes_from_flavor_suffix_sweep(self):
         self.assertEqual(
diff --git a/nova/virt/hardware.py b/nova/virt/hardware.py
index 65852c948251..4a275b6beb0c 100644
--- a/nova/virt/hardware.py
+++ b/nova/virt/hardware.py
@@ -1341,21 +1341,15 @@ def _get_numa_pagesize_constraint(flavor, image_meta):
             return MEMPAGES_LARGE
         elif request == "small":
             return MEMPAGES_SMALL
-        else:
-            try:
-                request = int(request)
-            except ValueError:
-                try:
-                    request = strutils.string_to_bytes(
-                        request, return_int=True) / units.Ki
-                except ValueError:
-                    request = 0
+        elif request.isdigit():
+            return int(request)
 
-        if request <= 0:
+        try:
+            return strutils.string_to_bytes(
+                request, return_int=True) / units.Ki
+        except ValueError:
             raise exception.MemoryPageSizeInvalid(pagesize=request)
 
-        return request
-
     flavor_request, image_request = _get_flavor_image_meta(
         'mem_page_size', flavor, image_meta)