diff --git a/build.gradle b/build.gradle
index 35173edd7..a5b6ef0d1 100644
--- a/build.gradle
+++ b/build.gradle
@@ -23,6 +23,9 @@
  * Optionally set NATIVE_TOOLCHAINS_DIR for easier reuse of toolchains which
  * take a lot to build and doesn't change often
  * -PNATIVE_TOOLCHAINS_DIR="/native/toolchains/path"
+ *
+ * Optionally set environement variables defined in prepare-toolchain-clang.sh
+ * to further customize the build
  */
 
 buildscript
diff --git a/misc/Android/prepare-toolchain-clang.sh b/misc/Android/prepare-toolchain-clang.sh
index a6624adde..d9fd13d50 100755
--- a/misc/Android/prepare-toolchain-clang.sh
+++ b/misc/Android/prepare-toolchain-clang.sh
@@ -110,6 +110,7 @@ define_default_value MVPTREE_SOURCE_VERSION origin/master
 define_default_value REPORT_DIR "$(pwd)/$(basename ${NATIVE_LIBS_TOOLCHAIN_PATH})_build_report/"
 
 define_default_value RS_SRC_DIR "$(realpath $(dirname $BASH_SOURCE)/../../)"
+define_default_value RS_EXTRA_CMAKE_OPTS ""
 
 
 cArch=""
@@ -827,15 +828,6 @@ build_phash()
 	popd
 }
 
-task_register fetch_jni_hpp
-fetch_jni_hpp()
-{
-	local rDir="supportlibs/jni.hpp/"
-
-	[ "$(ls "${RS_SRC_DIR}/${rDir}" | wc -l)" -gt "4" ] ||
-		git -C ${RS_SRC_DIR} submodule update --init ${rDir}
-}
-
 task_register build_mvptree
 build_mvptree()
 {
@@ -862,7 +854,8 @@ build_libretroshare()
 		-D RS_LIBRETROSHARE_STATIC=OFF -D RS_LIBRETROSHARE_SHARED=ON \
 		-D RS_BRODCAST_DISCOVERY=ON -D RS_EXPORT_JNI_ONLOAD=ON \
 		-D RS_SQLCIPHER=OFF -D RS_DH_PRIME_INIT_CHECK=OFF \
-		-D RS_FORUM_DEEP_INDEX=ON -D RS_JSON_API=ON || return $?
+		-D RS_FORUM_DEEP_INDEX=ON -D RS_JSON_API=ON \
+		$RS_EXTRA_CMAKE_OPTS || return $?
 	make -j${HOST_NUM_CPU} || return $?
 	make install || return $?
 	popd
@@ -887,7 +880,6 @@ build_default_toolchain()
 	task_run build_xapian || return $?
 	task_run build_miniupnpc || return $?
 	task_run build_phash || return $?
-#	task_run fetch_jni_hpp || return $?
 	task_run build_libretroshare || return $?
 #	task_run deduplicate_includes || return $?
 	task_run get_native_libs_toolchain_path || return $?