diff --git a/cmake/externals/sdl2/CMakeLists.txt b/cmake/externals/sdl2/CMakeLists.txt
index 635a1cb5bb..1e8e690743 100644
--- a/cmake/externals/sdl2/CMakeLists.txt
+++ b/cmake/externals/sdl2/CMakeLists.txt
@@ -19,6 +19,7 @@ elseif (APPLE)
     ExternalProject_Add(
       ${EXTERNAL_NAME}
       URL https://public.highfidelity.com/dependencies/SDL2-2.0.3.zip
+      URL_MD5 55f1eae5142d20db11c844d8d4d6deed
       CMAKE_ARGS -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR> -DVIDEO_OPENGL=OFF
       BINARY_DIR ${EXTERNAL_PROJECT_PREFIX}/build
       LOG_DOWNLOAD 1
diff --git a/cmake/externals/zlib/CMakeLists.txt b/cmake/externals/zlib/CMakeLists.txt
index 987ca1fd18..85506ba0e1 100644
--- a/cmake/externals/zlib/CMakeLists.txt
+++ b/cmake/externals/zlib/CMakeLists.txt
@@ -6,6 +6,7 @@ include(ExternalProject)
 ExternalProject_Add(
   ${EXTERNAL_NAME}
   URL https://public.highfidelity.com/dependencies/zlib128.zip
+  URL_MD5 126f8676442ffbd97884eb4d6f32afb4
   CMAKE_ARGS -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR>
   BINARY_DIR ${EXTERNAL_PROJECT_PREFIX}/build
   LOG_DOWNLOAD 1