diff --git a/app/witnesscalc/build_gmp.sh b/app/witnesscalc/build_gmp.sh
index 8f1b38049..b914bee4a 100755
--- a/app/witnesscalc/build_gmp.sh
+++ b/app/witnesscalc/build_gmp.sh
@@ -128,7 +128,7 @@ build_android()
         return 1
     fi
 
-    export TOOLCHAIN=$ANDROID_NDK/toolchains/llvm/prebuilt/linux-x86_64
+    export TOOLCHAIN=$ANDROID_NDK/toolchains/llvm/prebuilt/Darwin-x86_64
 
     export TARGET=aarch64-linux-android
     export API=21
@@ -173,7 +173,7 @@ build_android_x86_64()
         return 1
     fi
 
-    export TOOLCHAIN=$ANDROID_NDK/toolchains/llvm/prebuilt/linux-x86_64
+    export TOOLCHAIN=$ANDROID_NDK/toolchains/llvm/prebuilt/Darwin-x86_64
 
     export TARGET=x86_64-linux-android
     export API=21