diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 84f063f..d15158c 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/setup-go@v2
-      with: { go-version: ^1.14 }
+      with: { go-version: ^1.15 }
     - uses: actions/checkout@v2
     - name: build
       run: make build
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index a19a44f..d9e2ff8 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/setup-go@v2
-      with: { go-version: ^1.14 }
+      with: { go-version: ^1.15 }
     - uses: actions/checkout@v2
       with: { fetch-depth: 0 }
     - name: build
diff --git a/Dockerfile b/Dockerfile
index 30d7786..f3575ca 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,9 +1,11 @@
 
 # build image
 FROM golang:alpine as build
+WORKDIR /build
 RUN apk add --no-cache g++ make
+COPY go.sum go.mod Makefile /build/
+RUN make fetch
 COPY . /build/
-WORKDIR /build
 RUN make
 
 # runtime image