diff --git a/toolchain/mingw-toolchain.xml b/toolchain/mingw-toolchain.xml
index 6839a6704..33323dcb6 100644
--- a/toolchain/mingw-toolchain.xml
+++ b/toolchain/mingw-toolchain.xml
@@ -43,6 +43,7 @@
   <cppflag value="-std=c++11" if="HXCPP_CPP11" />
   <cppflag value="-U__STRICT_ANSI__" />
   <flag value="-m32" unless="HXCPP_M64"/>
+  <flag value="-m64" if="HXCPP_M64"/>
   <flag value="-DHXCPP_M64" if="HXCPP_M64"/>
   <flag value="-I${HXCPP}/include"/>
   <objdir value="obj/mingw${OBJEXT}/"/>
@@ -56,6 +57,7 @@
   <flag value="-debug" if="debug"/>
   <flag value="--enable-auto-import"/>
   <flag value="-m32" unless="HXCPP_M64"/>
+  <flag value="-m64" if="HXCPP_M64"/>
   <flag value="-static" if="no_shared_libs"/>
   <flag value="-static-libgcc" if="no_shared_libs"/>
   <flag value="-static-libstdc++" if="no_shared_libs"/>
@@ -70,6 +72,7 @@
   <flag value="-Wl,--enable-auto-import"/>
   <flag value="-mwindows" if="SUBSYSTEMWINDOWS" />
   <flag value="-m32" unless="HXCPP_M64"/>
+  <flag value="-m64" if="HXCPP_M64"/>
   <flag value="-static" if="no_shared_libs"/>
   <flag value="-static-libgcc" if="no_shared_libs" unless="linux_host"/>
   <flag value="-static-libstdc++" if="no_shared_libs" unless="linux_host"/>