Fixes
diff --git a/config.w32 b/config.w32
index 20ccf3a..67b5e2f 100644
--- a/config.w32
+++ b/config.w32
@@ -62,7 +62,7 @@
     "src\\core\\lib\\support\\tmpfile_windows.cc " +
     "src\\core\\lib\\support\\wrap_memcpy.cc " +
     "src\\core\\lib\\surface\\init.cc " +
-    "src\\core\\lib\\backoff\\backoff.c " +
+    "src\\core\\lib\\backoff\\backoff.cc " +
     "src\\core\\lib\\channel\\channel_args.cc " +
     "src\\core\\lib\\channel\\channel_stack.cc " +
     "src\\core\\lib\\channel\\channel_stack_builder.cc " +