diff --git a/Makefile b/Makefile
index 350d7b7..dd6ec49 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 CC = i686-w64-mingw32-gcc
 WINDRES = i686-w64-mingw32-windres
 CFLAGS = --std=c99 -O2 -I contrib/WinDivert-1.2.0-rc-MINGW/include/ -mwindows \
-    -mthreads -m32 -Wall
+    -mthreads -mno-ms-bitfields -m32 -Wall
 CLIBS = -lws2_32 -lkernel32 -L contrib/WinDivert-1.2.0-rc-MINGW/x86/ \
     -lWinDivert -lcomctl32 -mwindows
 OBJS = main.o redirect.o domain.o
diff --git a/redirect.c b/redirect.c
index 333e102..1986fd8 100644
--- a/redirect.c
+++ b/redirect.c
@@ -701,7 +701,7 @@ static void handle_dns(HANDLE handle, PWINDIVERT_ADDRESS addr,
     size_t len = sizeof(struct dnshdr) + data_len + sizeof(struct dnsa);
     if (len > 512)                          // Max DNS packet size.
         return;
-    len += sizeof(WINDIVERT_IPHDR) + sizeof(WINDIVERT_UDPHDR) + len;
+    len += sizeof(WINDIVERT_IPHDR) + sizeof(WINDIVERT_UDPHDR);
 
     char buf[len + 8];                      // 8 bytes extra.
     PWINDIVERT_IPHDR riphdr = (PWINDIVERT_IPHDR)buf;