diff --git a/external/external_build.cmake b/external/external_build.cmake
index d9b83d4..bbe3e77 100644
--- a/external/external_build.cmake
+++ b/external/external_build.cmake
@@ -234,6 +234,7 @@ if (INTERNAL_BOOST)
   ExternalProject_Add(boost
     URL ${BOOST_URL}
     PREFIX ${BUILD_PREFIX}/boost-prefix
+    URL_HASH MD5=da07ca30dd1c0d1fdedbd487efee01bd
     CONFIGURE_COMMAND 
            ${BOOST_SOURCE_DIR}/bootstrap.sh --prefix=${CMAKE_BINARY_DIR}/ext_build/boost
     BUILD_IN_SOURCE 1