diff --git a/src/dawn_wire/server/ServerBuffer.cpp b/src/dawn_wire/server/ServerBuffer.cpp
index 7005f38987..05be903a5c 100644
--- a/src/dawn_wire/server/ServerBuffer.cpp
+++ b/src/dawn_wire/server/ServerBuffer.cpp
@@ -74,8 +74,12 @@ namespace dawn_wire { namespace server {
         userdata->requestSerial = requestSerial;
         userdata->mode = mode;
 
-        if (offset64 > std::numeric_limits<size_t>::max() ||
-            size64 > std::numeric_limits<size_t>::max()) {
+        // Make sure that the deserialized offset and size are no larger than
+        // std::numeric_limits<size_t>::max() so that they are CPU-addressable, and size is not
+        // WGPU_WHOLE_MAP_SIZE, which is by definition std::numeric_limits<size_t>::max(). Since
+        // client does the default size computation, we should always have a valid actual size here
+        // in server. All other invalid actual size can be caught by dawn native side validation.
+        if (offset64 > std::numeric_limits<size_t>::max() || size64 >= WGPU_WHOLE_MAP_SIZE) {
             OnBufferMapAsyncCallback(WGPUBufferMapAsyncStatus_Error, userdata.get());
             return true;
         }