diff --git a/ci_build_global.sh b/ci_build_global.sh
index 0f7b14c..ce7036a 100755
--- a/ci_build_global.sh
+++ b/ci_build_global.sh
@@ -5,8 +5,12 @@ set -e
 export JDK_DEBUG_LEVEL=release
 
 if [[ "$BUILD_IOS" != "1" ]]; then
-  wget -nc -nv -O android-ndk-$NDK_VERSION-linux-x86_64.zip "https://dl.google.com/android/repository/android-ndk-$NDK_VERSION-linux-x86_64.zip"
-  ./extractndk.sh
+  if [[ -d $NDK ]]; then
+    echo "NDK already installed."
+  else 
+    wget -nc -nv -O android-ndk-$NDK_VERSION-linux-x86_64.zip "https://dl.google.com/android/repository/android-ndk-$NDK_VERSION-linux-x86_64.zip"
+    ./extractndk.sh
+  fi
   ./maketoolchain.sh
 else
   chmod +x ios-arm64-clang
diff --git a/maketoolchain.sh b/maketoolchain.sh
index d236f9e..9e8d8c5 100755
--- a/maketoolchain.sh
+++ b/maketoolchain.sh
@@ -2,9 +2,13 @@
 set -e
 
 . setdevkitpath.sh
-  
-$NDK/build/tools/make-standalone-toolchain.sh \
-	--arch=${TARGET_SHORT} \
-	--platform=android-21 \
-	--install-dir=$NDK/generated-toolchains/android-${TARGET_SHORT}-toolchain
+
+if [[ ! -f $NDK/generated-toolchains/android-${TARGET_SHORT}-toolchain/devkit.info.${TARGET_SHORT} ]]; then
+  $NDK/build/tools/make-standalone-toolchain.sh \
+	  --arch=${TARGET_SHORT} \
+	  --platform=android-21 \
+	  --install-dir=$NDK/generated-toolchains/android-${TARGET_SHORT}-toolchain
 cp devkit.info.${TARGET_SHORT} $NDK/generated-toolchains/android-${TARGET_SHORT}-toolchain/
+else
+  echo "NDK already has android-${TARGET_SHORT}-toolchain."
+fi
\ No newline at end of file
diff --git a/setdevkitpath.sh b/setdevkitpath.sh
index ffda375..6a50f7f 100755
--- a/setdevkitpath.sh
+++ b/setdevkitpath.sh
@@ -55,7 +55,9 @@ else
 export JVM_PLATFORM=linux
 # Set NDK
 export API=21
-export NDK=`pwd`/android-ndk-$NDK_VERSION
+if [[ -z "$NDK" ]]; then
+  export NDK=`pwd`/android-ndk-$NDK_VERSION
+fi
 export ANDROID_NDK_ROOT=$NDK 
 export TOOLCHAIN=$NDK/generated-toolchains/android-${TARGET_SHORT}-toolchain
 # export TOOLCHAIN=$NDK/toolchains/llvm/prebuilt/linux-x86_64