diff --git a/android/buildAndroidBOINC-CI.sh b/android/buildAndroidBOINC-CI.sh
index fcf9f1365f..8193701c86 100755
--- a/android/buildAndroidBOINC-CI.sh
+++ b/android/buildAndroidBOINC-CI.sh
@@ -19,6 +19,8 @@ set -e
 # along with BOINC.  If not, see <http://www.gnu.org/licenses/>.
 #
 
+# When you want to invalidate openssl and curl without change their versions.
+export REV=1
 export OPENSSL_VERSION=1.0.2s
 export CURL_VERSION=7.62.0
 export NDK_VERSION=21d
@@ -134,7 +136,7 @@ fi
 
 export COMPILEOPENSSL="no"
 export COMPILECURL="no"
-export NDK_FLAGFILE="$PREFIX/NDK-${NDK_VERSION}_done"
+export NDK_FLAGFILE="$PREFIX/NDK-${NDK_VERSION}-${REV}_done"
 export CURL_FLAGFILE="$PREFIX/curl-${CURL_VERSION}-${NDK_VERSION}-${arch}_done"
 export OPENSSL_FLAGFILE="$PREFIX/openssl-${OPENSSL_VERSION}-${NDK_VERSION}-${arch}_done"
 export CREATED_NDK_FOLDER=${CREATED_NDK_FOLDER:-"no"}
@@ -150,6 +152,12 @@ createNDKFolder()
 }
 
 if [ "$ci" = "yes" ]; then
+    if [ ! -e "${NDK_FLAGFILE}" ]; then
+        rm -rf "${PREFIX}/${arch}"
+        rm -rf "${OPENSSL_FLAGFILE}"
+        rm -rf "${CURL_FLAGFILE}"
+        touch "${NDK_FLAGFILE}"
+    fi
     createNDKFolder
 else
     if [ ! -e "${NDK_FLAGFILE}" ]; then