diff --git a/.travis.yml b/.travis.yml
index 827cd2b01..013e42628 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -90,32 +90,32 @@ matrix:
       dist: xenial
       env:
         - NAME=android-armv7
-        - BEFORE_BUILD="wget https://dl.google.com/android/repository/android-ndk-r18b-linux-x86_64.zip && unzip -q android-ndk-r18b-linux-x86_64.zip"
-        - BUILD="mkdir build && cd build && cmake -DCMAKE_TOOLCHAIN_FILE=`pwd`/android-ndk-r18b/build/cmake/android.toolchain.cmake -DANDROID_ABI=\"armeabi-v7a\" -DANDROID_ARM_NEON=ON -DANDROID_PLATFORM=android-14 .. && make -j2"
+        - BEFORE_BUILD="wget https://dl.google.com/android/repository/android-ndk-r19c-linux-x86_64.zip && unzip -q android-ndk-r19c-linux-x86_64.zip"
+        - BUILD="mkdir build && cd build && cmake -DCMAKE_TOOLCHAIN_FILE=`pwd`/android-ndk-r19c/build/cmake/android.toolchain.cmake -DANDROID_ABI=\"armeabi-v7a\" -DANDROID_ARM_NEON=ON -DANDROID_PLATFORM=android-14 .. && make -j2"
 
     - name: "android-armv7-gpu"
       os: linux
       dist: xenial
       env:
         - NAME=android-armv7-gpu
-        - BEFORE_BUILD="wget https://sdk.lunarg.com/sdk/download/1.1.92.1/linux/vulkansdk-linux-x86_64-1.1.92.1.tar.gz?Human=true -O vulkansdk-linux-x86_64-1.1.92.1.tar.gz && tar -xf vulkansdk-linux-x86_64-1.1.92.1.tar.gz && wget https://dl.google.com/android/repository/android-ndk-r18b-linux-x86_64.zip && unzip -q android-ndk-r18b-linux-x86_64.zip"
-        - BUILD="export PATH=`pwd`/1.1.92.1/x86_64/bin:$PATH && mkdir build && cd build && cmake -DCMAKE_TOOLCHAIN_FILE=`pwd`/android-ndk-r18b/build/cmake/android.toolchain.cmake -DANDROID_ABI=\"armeabi-v7a\" -DANDROID_ARM_NEON=ON -DANDROID_PLATFORM=android-24 -DNCNN_VULKAN=ON .. && make -j2"
+        - BEFORE_BUILD="wget https://sdk.lunarg.com/sdk/download/1.1.92.1/linux/vulkansdk-linux-x86_64-1.1.92.1.tar.gz?Human=true -O vulkansdk-linux-x86_64-1.1.92.1.tar.gz && tar -xf vulkansdk-linux-x86_64-1.1.92.1.tar.gz && wget https://dl.google.com/android/repository/android-ndk-r19c-linux-x86_64.zip && unzip -q android-ndk-r19c-linux-x86_64.zip"
+        - BUILD="export PATH=`pwd`/1.1.92.1/x86_64/bin:$PATH && mkdir build && cd build && cmake -DCMAKE_TOOLCHAIN_FILE=`pwd`/android-ndk-r19c/build/cmake/android.toolchain.cmake -DANDROID_ABI=\"armeabi-v7a\" -DANDROID_ARM_NEON=ON -DANDROID_PLATFORM=android-24 -DNCNN_VULKAN=ON .. && make -j2"
 
     - name: "android-aarch64"
       os: linux
       dist: xenial
       env:
         - NAME=android-aarch64
-        - BEFORE_BUILD="wget https://dl.google.com/android/repository/android-ndk-r18b-linux-x86_64.zip && unzip -q android-ndk-r18b-linux-x86_64.zip"
-        - BUILD="mkdir build && cd build && cmake -DCMAKE_TOOLCHAIN_FILE=`pwd`/android-ndk-r18b/build/cmake/android.toolchain.cmake -DANDROID_ABI=\"arm64-v8a\" -DANDROID_PLATFORM=android-21 .. && make -j2"
+        - BEFORE_BUILD="wget https://dl.google.com/android/repository/android-ndk-r19c-linux-x86_64.zip && unzip -q android-ndk-r19c-linux-x86_64.zip"
+        - BUILD="mkdir build && cd build && cmake -DCMAKE_TOOLCHAIN_FILE=`pwd`/android-ndk-r19c/build/cmake/android.toolchain.cmake -DANDROID_ABI=\"arm64-v8a\" -DANDROID_PLATFORM=android-21 .. && make -j2"
 
     - name: "android-aarch64-gpu"
       os: linux
       dist: xenial
       env:
         - NAME=android-aarch64-gpu
-        - BEFORE_BUILD="wget https://sdk.lunarg.com/sdk/download/1.1.92.1/linux/vulkansdk-linux-x86_64-1.1.92.1.tar.gz?Human=true -O vulkansdk-linux-x86_64-1.1.92.1.tar.gz && tar -xf vulkansdk-linux-x86_64-1.1.92.1.tar.gz && wget https://dl.google.com/android/repository/android-ndk-r18b-linux-x86_64.zip && unzip -q android-ndk-r18b-linux-x86_64.zip"
-        - BUILD="export PATH=`pwd`/1.1.92.1/x86_64/bin:$PATH && mkdir build && cd build && cmake -DCMAKE_TOOLCHAIN_FILE=`pwd`/android-ndk-r18b/build/cmake/android.toolchain.cmake -DANDROID_ABI=\"arm64-v8a\" -DANDROID_PLATFORM=android-24 -DNCNN_VULKAN=ON .. && make -j2"
+        - BEFORE_BUILD="wget https://sdk.lunarg.com/sdk/download/1.1.92.1/linux/vulkansdk-linux-x86_64-1.1.92.1.tar.gz?Human=true -O vulkansdk-linux-x86_64-1.1.92.1.tar.gz && tar -xf vulkansdk-linux-x86_64-1.1.92.1.tar.gz && wget https://dl.google.com/android/repository/android-ndk-r19c-linux-x86_64.zip && unzip -q android-ndk-r19c-linux-x86_64.zip"
+        - BUILD="export PATH=`pwd`/1.1.92.1/x86_64/bin:$PATH && mkdir build && cd build && cmake -DCMAKE_TOOLCHAIN_FILE=`pwd`/android-ndk-r19c/build/cmake/android.toolchain.cmake -DANDROID_ABI=\"arm64-v8a\" -DANDROID_PLATFORM=android-24 -DNCNN_VULKAN=ON .. && make -j2"
 
     - name: "ios-iphoneos"
       os: osx