diff --git a/Dockerfile.arm32v7 b/Dockerfile.arm32v7
index 7baf625..5829201 100644
--- a/Dockerfile.arm32v7
+++ b/Dockerfile.arm32v7
@@ -3,8 +3,8 @@ FROM arm32v7/ubuntu:18.04
 RUN apt-get update && apt-get install -y wget git make llvm-8 llvm-8-dev g++ libsqlite3-dev libyaml-dev libgc-dev libssl-dev libcrypto++-dev libevent-dev libgmp-dev zlib1g-dev libpcre++-dev pkg-config libarchive-dev libxml2-dev libacl1-dev nettle-dev liblzo2-dev liblzma-dev libbz2-dev
 
 RUN git clone https://github.com/crystal-lang/crystal && cd crystal && git checkout 0.34.0 && make deps && cd ..
-RUN git clone https://github.com/kostya/myhtml && cd myhtml/src/ext && git checkout 1.5.0 && make && cd ..
-RUN git clone https://github.com/jessedoyle/duktape.cr && cd duktape.cr/ext && git checkout 0.20.0 && make && cd ..
+RUN git clone https://github.com/kostya/myhtml && cd myhtml/src/ext && git checkout v1.5.0 && make && cd ..
+RUN git clone https://github.com/jessedoyle/duktape.cr && cd duktape.cr/ext && git checkout v0.20.0 && make && cd ..
 
 COPY mango-arm32v7.o .
 
diff --git a/Dockerfile.arm64v8 b/Dockerfile.arm64v8
index 30ef6b2..a431adc 100644
--- a/Dockerfile.arm64v8
+++ b/Dockerfile.arm64v8
@@ -3,8 +3,8 @@ FROM arm64v8/ubuntu:18.04
 RUN apt-get update && apt-get install -y wget git make llvm-8 llvm-8-dev g++ libsqlite3-dev libyaml-dev libgc-dev libssl-dev libcrypto++-dev libevent-dev libgmp-dev zlib1g-dev libpcre++-dev pkg-config libarchive-dev libxml2-dev libacl1-dev nettle-dev liblzo2-dev liblzma-dev libbz2-dev
 
 RUN git clone https://github.com/crystal-lang/crystal && cd crystal && git checkout 0.34.0 && make deps && cd ..
-RUN git clone https://github.com/kostya/myhtml && cd myhtml/src/ext && git checkout 1.5.0 && make && cd ..
-RUN git clone https://github.com/jessedoyle/duktape.cr && cd duktape.cr/ext && git checkout 0.20.0 && make && cd ..
+RUN git clone https://github.com/kostya/myhtml && cd myhtml/src/ext && git checkout v1.5.0 && make && cd ..
+RUN git clone https://github.com/jessedoyle/duktape.cr && cd duktape.cr/ext && git checkout v0.20.0 && make && cd ..
 
 COPY mango-arm64v8.o .