diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index e1887fa..a810a28 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -225,7 +225,7 @@ jobs:
           docker run --rm -v "$(pwd):/argon2id" -w /argon2id \
             --platform=linux/arm64 \
             ruby:${{ matrix.ruby }}-alpine \
-            sh -c "gem update --system && apk add bash && ./scripts/test-gem-install"
+            ./scripts/test-gem-install
 
   test-precompiled-arm-linux-gnu:
     needs: "precompile-arm-linux-gnu"
@@ -246,7 +246,7 @@ jobs:
           docker run --rm -v "$(pwd):/argon2id" -w /argon2id \
             --platform=linux/arm/v7 \
             ruby:${{ matrix.ruby }} \
-            sh -c "gem update --system && ./scripts/test-gem-install"
+            ./scripts/test-gem-install
 
   test-precompiled-arm-linux-musl:
     needs: "precompile-arm-linux-musl"
@@ -267,7 +267,7 @@ jobs:
           docker run --rm -v "$(pwd):/argon2id" -w /argon2id \
             --platform=linux/arm/v7 \
             ruby:${{ matrix.ruby }}-alpine \
-            sh -c "gem update --system && apk add bash && ./scripts/test-gem-install"
+            ./scripts/test-gem-install
 
   test-precompiled-x86-linux-gnu:
     needs: "precompile-x86-linux-gnu"
@@ -309,7 +309,7 @@ jobs:
           docker run --rm -v "$(pwd):/argon2id" -w /argon2id \
             --platform=linux/386 \
             ruby:${{ matrix.ruby }}-alpine \
-            sh -c "gem update --system && apk add bash && ./scripts/test-gem-install"
+            ./scripts/test-gem-install
 
   test-precompiled-x86_64-linux-gnu:
     needs: "precompile-x86_64-linux-gnu"
@@ -347,7 +347,6 @@ jobs:
         with:
           name: cruby-x86_64-linux-musl-gem
           path: pkg
-      - run: apk add bash
       - run: ./scripts/test-gem-install
 
   test-precompiled-arm64-darwin:
diff --git a/scripts/test-gem-install b/scripts/test-gem-install
index a0fc6b6..fe3f5c0 100755
--- a/scripts/test-gem-install
+++ b/scripts/test-gem-install
@@ -1,8 +1,8 @@
-#!/usr/bin/env bash
+#!/usr/bin/env sh
 
 set -eu
 
-gem install --no-document pkg/*.gem -- "$@"
+gem install --no-document pkg/*.gem
 cd "$(dirname "$(gem which argon2id)")/.."
 bundle
 bundle exec rake test