diff --git a/CMakeFilters.cmake b/CMakeFilters.cmake
index da8e2c74ff4..72f7f459427 100644
--- a/CMakeFilters.cmake
+++ b/CMakeFilters.cmake
@@ -36,8 +36,8 @@ include (ExternalProject)
 set (HDF5_ALLOW_EXTERNAL_SUPPORT "NO" CACHE STRING "Allow External Library Building (NO GIT TGZ)")
 set_property (CACHE HDF5_ALLOW_EXTERNAL_SUPPORT PROPERTY STRINGS NO GIT TGZ)
 if (HDF5_ALLOW_EXTERNAL_SUPPORT MATCHES "GIT" OR HDF5_ALLOW_EXTERNAL_SUPPORT MATCHES "TGZ")
-  set (ZLIB_USE_EXTERNAL ON CACHE BOOL "Use External Library Building for ZLIB")
-  set (SZIP_USE_EXTERNAL ON CACHE BOOL "Use External Library Building for SZIP")
+  set (ZLIB_USE_EXTERNAL ON CACHE BOOL "Use External Library Building for ZLIB" FORCE)
+  set (SZIP_USE_EXTERNAL ON CACHE BOOL "Use External Library Building for SZIP" FORCE)
   if (HDF5_ALLOW_EXTERNAL_SUPPORT MATCHES "GIT")
     set (ZLIB_URL ${ZLIB_GIT_URL} CACHE STRING "Path to zlib git repository")
     set (ZLIB_BRANCH ${ZLIB_GIT_BRANCH})
diff --git a/CMakePlugins.cmake b/CMakePlugins.cmake
index bc1074fbba3..7fd332a2ebe 100644
--- a/CMakePlugins.cmake
+++ b/CMakePlugins.cmake
@@ -26,7 +26,7 @@ include (ExternalProject)
 set (HDF5_ALLOW_EXTERNAL_SUPPORT "NO" CACHE STRING "Allow External Library Building (NO GIT TGZ)")
 set_property (CACHE HDF5_ALLOW_EXTERNAL_SUPPORT PROPERTY STRINGS NO GIT TGZ)
 if (HDF5_ALLOW_EXTERNAL_SUPPORT MATCHES "GIT" OR HDF5_ALLOW_EXTERNAL_SUPPORT MATCHES "TGZ")
-  set (PLUGIN_USE_EXTERNAL ON CACHE BOOL "Use External Library Building for PLUGIN")
+  set (PLUGIN_USE_EXTERNAL ON CACHE BOOL "Use External Library Building for PLUGIN" FORCE)
   if (HDF5_ALLOW_EXTERNAL_SUPPORT MATCHES "GIT")
     set (PLUGIN_URL ${PLUGIN_GIT_URL} CACHE STRING "Path to PLUGIN git repository")
     set (PLUGIN_BRANCH ${PLUGIN_GIT_BRANCH})