diff --git a/modules/beast_core/zip/GZIPDecompressorInputStream.cpp b/modules/beast_core/zip/GZIPDecompressorInputStream.cpp
index 9255b4fae0..b044649714 100644
--- a/modules/beast_core/zip/GZIPDecompressorInputStream.cpp
+++ b/modules/beast_core/zip/GZIPDecompressorInputStream.cpp
@@ -67,6 +67,9 @@ namespace zlibNamespace
   #undef fdopen
   #undef local
   #undef Code
+  #undef Dad
+  #undef Len
+  #undef Freq
 
   #if BEAST_CLANG
    #pragma clang diagnostic pop