diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 2833b0c1..a2237004 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -70,16 +70,21 @@ jobs:
         run: erl -version
       - name: Output Elixir version
         run: echo "Elixir ${{steps.setup-elixir.outputs.elixir-version}}"
+        if: ${{matrix.pair.elixir-version}}
       - name: Run Mix project tests
         run: |-
           cd test-projects/mix
           mix deps.get
           mix test
+        if: ${{matrix.pair.elixir-version}}
       - name: Run rebar3 project tests
         run: |
           cd test-projects/rebar3
           rebar3 as test do xref,dialyzer,ct,cover
+        if: ${{matrix.pair.rebar3-version}}
       - name: Output rebar3 version
         run: echo "rebar3 ${{steps.setup-elixir.outputs.rebar3-version}}"
+        if: ${{matrix.pair.rebar3-version}}
       - name: Check rebar3 version
         run: rebar3 version
+        if: ${{matrix.pair.rebar3-version}}
diff --git a/__tests__/setup-beam.test.js b/__tests__/setup-beam.test.js
index 967c792a..a599c5ea 100644
--- a/__tests__/setup-beam.test.js
+++ b/__tests__/setup-beam.test.js
@@ -12,13 +12,13 @@ async function test() {
   vsn = await setupElixir.getOTPVersion('^19.3', 'ubuntu-18.04')
   deepStrictEqual(vsn, 'OTP-19.3.6')
 
-  vsn = await setupElixir.getElixirVersion('v1.10.x', '23')
+  vsn = await setupElixir.getElixirVersion('v1.10.x', 'OTP-23')
   deepStrictEqual(vsn, ['v1.10.4', '23'])
 
-  vsn = await setupElixir.getElixirVersion('^v1.10', '23')
-  deepStrictEqual(vsn, ['v1.10.4', '23'])
+  vsn = await setupElixir.getElixirVersion('^v1.10', 'OTP-23')
+  deepStrictEqual(vsn, ['v1.11.3', '23'])
 
-  vsn = await setupElixir.getElixirVersion('v1.11.0-rc.0', '23')
+  vsn = await setupElixir.getElixirVersion('v1.11.0-rc.0', 'OTP-23')
   deepStrictEqual(vsn, ['v1.11.0-rc.0', '23'])
 
   vsn = await setupElixir.getRebar3Version('3.x')
diff --git a/dist/.github/workflows/test.yml b/dist/.github/workflows/test.yml
index 519a628c..a2237004 100644
--- a/dist/.github/workflows/test.yml
+++ b/dist/.github/workflows/test.yml
@@ -27,7 +27,7 @@ jobs:
     name: >
       Pre-release integration tests
       (Erlang/OTP ${{matrix.pair.otp-version}},
-       Elixir ${{matrix.pair.elixir-version},
+       Elixir ${{matrix.pair.elixir-version}},
        rebar3 ${{matrix.pair.rebar3-version}})
     runs-on: ubuntu-latest
     strategy:
@@ -70,16 +70,21 @@ jobs:
         run: erl -version
       - name: Output Elixir version
         run: echo "Elixir ${{steps.setup-elixir.outputs.elixir-version}}"
+        if: ${{matrix.pair.elixir-version}}
       - name: Run Mix project tests
         run: |-
           cd test-projects/mix
           mix deps.get
           mix test
+        if: ${{matrix.pair.elixir-version}}
       - name: Run rebar3 project tests
         run: |
           cd test-projects/rebar3
           rebar3 as test do xref,dialyzer,ct,cover
+        if: ${{matrix.pair.rebar3-version}}
       - name: Output rebar3 version
         run: echo "rebar3 ${{steps.setup-elixir.outputs.rebar3-version}}"
+        if: ${{matrix.pair.rebar3-version}}
       - name: Check rebar3 version
         run: rebar3 version
+        if: ${{matrix.pair.rebar3-version}}
diff --git a/dist/.github1/workflows/test.yml b/dist/.github1/workflows/test.yml
index 519a628c..a2237004 100644
--- a/dist/.github1/workflows/test.yml
+++ b/dist/.github1/workflows/test.yml
@@ -27,7 +27,7 @@ jobs:
     name: >
       Pre-release integration tests
       (Erlang/OTP ${{matrix.pair.otp-version}},
-       Elixir ${{matrix.pair.elixir-version},
+       Elixir ${{matrix.pair.elixir-version}},
        rebar3 ${{matrix.pair.rebar3-version}})
     runs-on: ubuntu-latest
     strategy:
@@ -70,16 +70,21 @@ jobs:
         run: erl -version
       - name: Output Elixir version
         run: echo "Elixir ${{steps.setup-elixir.outputs.elixir-version}}"
+        if: ${{matrix.pair.elixir-version}}
       - name: Run Mix project tests
         run: |-
           cd test-projects/mix
           mix deps.get
           mix test
+        if: ${{matrix.pair.elixir-version}}
       - name: Run rebar3 project tests
         run: |
           cd test-projects/rebar3
           rebar3 as test do xref,dialyzer,ct,cover
+        if: ${{matrix.pair.rebar3-version}}
       - name: Output rebar3 version
         run: echo "rebar3 ${{steps.setup-elixir.outputs.rebar3-version}}"
+        if: ${{matrix.pair.rebar3-version}}
       - name: Check rebar3 version
         run: rebar3 version
+        if: ${{matrix.pair.rebar3-version}}
diff --git a/dist/__tests__/setup-elixir.test.js b/dist/__tests__/setup-elixir.test.js
index f73f7cbd..04bacd37 100644
--- a/dist/__tests__/setup-elixir.test.js
+++ b/dist/__tests__/setup-elixir.test.js
@@ -19,13 +19,13 @@ async function test() {
   vsn = await setupElixir.getOTPVersion('^19.3', 'ubuntu-18.04')
   deepStrictEqual(vsn, 'OTP-19.3.6')
 
-  vsn = await setupElixir.getElixirVersion('v1.10.x', '23')
+  vsn = await setupElixir.getElixirVersion('v1.10.x', 'OTP-23')
   deepStrictEqual(vsn, ['v1.10.4', '23'])
 
-  vsn = await setupElixir.getElixirVersion('^v1.10', '23')
-  deepStrictEqual(vsn, ['v1.10.4', '23'])
+  vsn = await setupElixir.getElixirVersion('^v1.10', 'OTP-23')
+  deepStrictEqual(vsn, ['v1.11.3', '23'])
 
-  vsn = await setupElixir.getElixirVersion('v1.11.0-rc.0', '23')
+  vsn = await setupElixir.getElixirVersion('v1.11.0-rc.0', 'OTP-23')
   deepStrictEqual(vsn, ['v1.11.0-rc.0', '23'])
 
   vsn = await setupElixir.getRebar3Version('3.x')
@@ -3930,12 +3930,12 @@ const path = __nccwpck_require__(5622)
 /**
  * Install Erlang/OTP.
  *
- * @param {string} version
  * @param {string} osVersion
+ * @param {string} version
  */
-async function installOTP(version, osVersion) {
+async function installOTP(osVersion, version) {
   checkPlatform()
-  await exec(__nccwpck_require__.ab + "install-otp1", [version, osVersion])
+  await exec(__nccwpck_require__.ab + "install-otp1", [osVersion, version])
 }
 
 /**
@@ -4009,7 +4009,7 @@ async function main() {
 
   // Elixir - optional
   const elixirSpec = getElixirSpecFromInput()
-  if (elixirSpec != undefined) {
+  if (elixirSpec) {
     const [elixirVersion, otpMajor] = await getElixirVersion(
       elixirSpec,
       otpVersion,
@@ -4024,7 +4024,7 @@ async function main() {
 
   // rebar3 - optional
   const rebar3Spec = getRebar3SpecFromInput()
-  if (rebar3Spec != undefined) {
+  if (rebar3Spec) {
     const rebar3Version = await getRebar3Version(rebar3Spec)
     console.log(`##[group]Installing rebar3 ${rebar3Version}`)
     await installer.installRebar3(rebar3Version)
@@ -4032,19 +4032,20 @@ async function main() {
     core.setOutput('rebar3-version', otpVersion)
   }
 
-  process.env.PATH = `${process.env.RUNNER_TEMP}/.setup-elixir/otp/bin`
-  process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/elixir/bin`
-  process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/rebar3/bin`
-  process.env.PATH += `:${process.env.PATH}`
-
   // mix - optional
-  let installHex = core.getInput('install-hex')
-  installHex = installHex == null ? 'true' : installHex
-  if (installRebar === 'true') await exec('mix local.rebar --force')
+  if (elixirSpec) {
+    process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/otp/bin`
+    process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/elixir/bin`
+    process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/rebar3/bin`
+
+    let installRebar = core.getInput('install-rebar')
+    installRebar = installRebar == null ? 'true' : installRebar
+    installRebar && await exec('mix local.rebar --force')
 
-  let installRebar = core.getInput('install-rebar')
-  installRebar = installRebar == null ? 'true' : installRebar
-  if (installHex === 'true') await exec('mix local.hex --force')
+    let installHex = core.getInput('install-hex')
+    installHex = installHex == null ? 'true' : installHex
+    installHex && await exec('mix local.hex --force')
+  }
 }
 
 function getOTPSpecFromInput() {
@@ -4059,7 +4060,7 @@ function getElixirSpecFromInput() {
   if (process.env.CI_TEST_ENV === 'test') {
     return process.env.CI_TEST_ELIXIR_VSN;
   } else {
-    core.getInput('elixir-version', {required: false}) || undefined;
+    return core.getInput('elixir-version', {required: false});
   }
 }
 
@@ -4067,7 +4068,7 @@ function getRebar3SpecFromInput() {
   if (process.env.CI_TEST_ENV === 'test') {
     return process.env.CI_TEST_REBAR3_VSN;
   } else {
-    return core.getInput('rebar3-version', {required: false}) || undefined;
+    return core.getInput('rebar3-version', {required: false});
   }
 }
 
@@ -4098,8 +4099,8 @@ async function getElixirVersion(spec, otpVersion) {
   const gitRef = version ? `v${version}` : spec
   const otpMatch = otpVersion.match(/^OTP-([\.\d]+)/)
 
-  if (otpMatch != null && versions.get(gitRef).includes(otpMatch[0])) {
-    return [gitRef, otpMatch[0]]
+  if (otpMatch && versions.get(gitRef).includes(otpMatch[1])) {
+    return [gitRef, otpMatch[1]]
   } else {
     return [gitRef, null]
   }
@@ -4178,7 +4179,7 @@ async function getRebar3Version(spec) {
 }
 
 function get(url, testFile) {
-  if (process.env.NODE_ENV === 'test' && testFile !== undefined) {
+  if (process.env.NODE_ENV === 'test' && testFile) {
     return readFile(__nccwpck_require__.ab + "__tests__1/" + testFile)
       .then((buf) => buf.toString())
   }
diff --git a/dist/__tests__1/setup-elixir.test.js b/dist/__tests__1/setup-elixir.test.js
index 967c792a..a599c5ea 100644
--- a/dist/__tests__1/setup-elixir.test.js
+++ b/dist/__tests__1/setup-elixir.test.js
@@ -12,13 +12,13 @@ async function test() {
   vsn = await setupElixir.getOTPVersion('^19.3', 'ubuntu-18.04')
   deepStrictEqual(vsn, 'OTP-19.3.6')
 
-  vsn = await setupElixir.getElixirVersion('v1.10.x', '23')
+  vsn = await setupElixir.getElixirVersion('v1.10.x', 'OTP-23')
   deepStrictEqual(vsn, ['v1.10.4', '23'])
 
-  vsn = await setupElixir.getElixirVersion('^v1.10', '23')
-  deepStrictEqual(vsn, ['v1.10.4', '23'])
+  vsn = await setupElixir.getElixirVersion('^v1.10', 'OTP-23')
+  deepStrictEqual(vsn, ['v1.11.3', '23'])
 
-  vsn = await setupElixir.getElixirVersion('v1.11.0-rc.0', '23')
+  vsn = await setupElixir.getElixirVersion('v1.11.0-rc.0', 'OTP-23')
   deepStrictEqual(vsn, ['v1.11.0-rc.0', '23'])
 
   vsn = await setupElixir.getRebar3Version('3.x')
diff --git a/dist/index.js b/dist/index.js
index 26f65f94..50f04917 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -3884,12 +3884,12 @@ const path = __nccwpck_require__(5622)
 /**
  * Install Erlang/OTP.
  *
- * @param {string} version
  * @param {string} osVersion
+ * @param {string} version
  */
-async function installOTP(version, osVersion) {
+async function installOTP(osVersion, version) {
   checkPlatform()
-  await exec(__nccwpck_require__.ab + "install-otp", [version, osVersion])
+  await exec(__nccwpck_require__.ab + "install-otp", [osVersion, version])
 }
 
 /**
@@ -3963,7 +3963,7 @@ async function main() {
 
   // Elixir - optional
   const elixirSpec = getElixirSpecFromInput()
-  if (elixirSpec != undefined) {
+  if (elixirSpec) {
     const [elixirVersion, otpMajor] = await getElixirVersion(
       elixirSpec,
       otpVersion,
@@ -3978,7 +3978,7 @@ async function main() {
 
   // rebar3 - optional
   const rebar3Spec = getRebar3SpecFromInput()
-  if (rebar3Spec != undefined) {
+  if (rebar3Spec) {
     const rebar3Version = await getRebar3Version(rebar3Spec)
     console.log(`##[group]Installing rebar3 ${rebar3Version}`)
     await installer.installRebar3(rebar3Version)
@@ -3986,19 +3986,20 @@ async function main() {
     core.setOutput('rebar3-version', otpVersion)
   }
 
-  process.env.PATH = `${process.env.RUNNER_TEMP}/.setup-elixir/otp/bin`
-  process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/elixir/bin`
-  process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/rebar3/bin`
-  process.env.PATH += `:${process.env.PATH}`
-
   // mix - optional
-  let installHex = core.getInput('install-hex')
-  installHex = installHex == null ? 'true' : installHex
-  if (installRebar === 'true') await exec('mix local.rebar --force')
+  if (elixirSpec) {
+    process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/otp/bin`
+    process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/elixir/bin`
+    process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/rebar3/bin`
 
-  let installRebar = core.getInput('install-rebar')
-  installRebar = installRebar == null ? 'true' : installRebar
-  if (installHex === 'true') await exec('mix local.hex --force')
+    let installRebar = core.getInput('install-rebar')
+    installRebar = installRebar == null ? 'true' : installRebar
+    installRebar && await exec('mix local.rebar --force')
+
+    let installHex = core.getInput('install-hex')
+    installHex = installHex == null ? 'true' : installHex
+    installHex && await exec('mix local.hex --force')
+  }
 }
 
 function getOTPSpecFromInput() {
@@ -4013,7 +4014,7 @@ function getElixirSpecFromInput() {
   if (process.env.CI_TEST_ENV === 'test') {
     return process.env.CI_TEST_ELIXIR_VSN;
   } else {
-    core.getInput('elixir-version', {required: false}) || undefined;
+    return core.getInput('elixir-version', {required: false});
   }
 }
 
@@ -4021,7 +4022,7 @@ function getRebar3SpecFromInput() {
   if (process.env.CI_TEST_ENV === 'test') {
     return process.env.CI_TEST_REBAR3_VSN;
   } else {
-    return core.getInput('rebar3-version', {required: false}) || undefined;
+    return core.getInput('rebar3-version', {required: false});
   }
 }
 
@@ -4052,8 +4053,8 @@ async function getElixirVersion(spec, otpVersion) {
   const gitRef = version ? `v${version}` : spec
   const otpMatch = otpVersion.match(/^OTP-([\.\d]+)/)
 
-  if (otpMatch != null && versions.get(gitRef).includes(otpMatch[0])) {
-    return [gitRef, otpMatch[0]]
+  if (otpMatch && versions.get(gitRef).includes(otpMatch[1])) {
+    return [gitRef, otpMatch[1]]
   } else {
     return [gitRef, null]
   }
@@ -4132,7 +4133,7 @@ async function getRebar3Version(spec) {
 }
 
 function get(url, testFile) {
-  if (process.env.NODE_ENV === 'test' && testFile !== undefined) {
+  if (process.env.NODE_ENV === 'test' && testFile) {
     return readFile(__nccwpck_require__.ab + "__tests__/" + testFile)
       .then((buf) => buf.toString())
   }
diff --git a/dist/install-elixir b/dist/install-elixir
index 2e7a08a0..41fb90a8 100755
--- a/dist/install-elixir
+++ b/dist/install-elixir
@@ -4,14 +4,7 @@ set -eo pipefail
 
 cd "$RUNNER_TEMP"
 
-<<<<<<< HEAD
-wget -q https://repo.hex.pm/builds/elixir/${1}${2}.zip
-unzip -d .setup-beam/elixir ${1}${2}.zip
-rm ${1}${2}.zip
-echo "$(pwd)/.setup-beam/elixir/bin" >> $GITHUB_PATH
-=======
-wget -q https://repo.hex.pm/builds/elixir/"${1}""${2}".zip
-unzip -d .setup-elixir/elixir "${1}""${2}".zip
-rm "${1}""${2}".zip
+wget -q "https://repo.hex.pm/builds/elixir/${1}${2}.zip"
+unzip -d .setup-elixir/elixir "${1}${2}.zip"
+rm -f "${1}${2}.zip"
 echo "$(pwd)/.setup-elixir/elixir/bin" >> "$GITHUB_PATH"
->>>>>>> Merge setup-erlang in
diff --git a/dist/install-elixir1 b/dist/install-elixir1
index 9b7de466..41fb90a8 100755
--- a/dist/install-elixir1
+++ b/dist/install-elixir1
@@ -4,7 +4,7 @@ set -eo pipefail
 
 cd "$RUNNER_TEMP"
 
-wget -q https://repo.hex.pm/builds/elixir/"${1}""${2}".zip
-unzip -d .setup-elixir/elixir "${1}""${2}".zip
-rm "${1}""${2}".zip
+wget -q "https://repo.hex.pm/builds/elixir/${1}${2}.zip"
+unzip -d .setup-elixir/elixir "${1}${2}.zip"
+rm -f "${1}${2}.zip"
 echo "$(pwd)/.setup-elixir/elixir/bin" >> "$GITHUB_PATH"
diff --git a/dist/install-otp b/dist/install-otp
index 175c44a4..d6e55c43 100755
--- a/dist/install-otp
+++ b/dist/install-otp
@@ -4,9 +4,12 @@ set -eo pipefail
 
 cd "$RUNNER_TEMP"
 
-wget -q -O otp.tar.gz https://repo.hex.pm/builds/otp/"${2}"/"${1}".tar.gz
+OS=${1}
+OTP=${2}
+
+wget -q -O otp.tar.gz "https://repo.hex.pm/builds/otp/${OS}/${OTP}.tar.gz"
 mkdir -p .setup-elixir/otp
 tar zxf otp.tar.gz -C .setup-elixir/otp --strip-components=1
-rm otp.tar.gz
-.setup-elixir/otp/Install -minimal "$(pwd)"/.setup-elixir/otp
+rm -f otp.tar.gz
+.setup-elixir/otp/Install -minimal "$(pwd)/.setup-elixir/otp"
 echo "$(pwd)/.setup-elixir/otp/bin" >> "$GITHUB_PATH"
diff --git a/dist/install-otp1 b/dist/install-otp1
index 175c44a4..d6e55c43 100755
--- a/dist/install-otp1
+++ b/dist/install-otp1
@@ -4,9 +4,12 @@ set -eo pipefail
 
 cd "$RUNNER_TEMP"
 
-wget -q -O otp.tar.gz https://repo.hex.pm/builds/otp/"${2}"/"${1}".tar.gz
+OS=${1}
+OTP=${2}
+
+wget -q -O otp.tar.gz "https://repo.hex.pm/builds/otp/${OS}/${OTP}.tar.gz"
 mkdir -p .setup-elixir/otp
 tar zxf otp.tar.gz -C .setup-elixir/otp --strip-components=1
-rm otp.tar.gz
-.setup-elixir/otp/Install -minimal "$(pwd)"/.setup-elixir/otp
+rm -f otp.tar.gz
+.setup-elixir/otp/Install -minimal "$(pwd)/.setup-elixir/otp"
 echo "$(pwd)/.setup-elixir/otp/bin" >> "$GITHUB_PATH"
diff --git a/dist/install-rebar3 b/dist/install-rebar3
index 686b74d5..ba80ba06 100755
--- a/dist/install-rebar3
+++ b/dist/install-rebar3
@@ -6,9 +6,9 @@ cd "$RUNNER_TEMP"
 
 VSN=${1}
 FILE=rebar3
-DIR_FOR_BIN=.setup-elixir/rebar3
+DIR_FOR_BIN=.setup-elixir/rebar3/bin
 
-wget -q https://github.com/erlang/rebar3/releases/download/"${VSN}"/"${FILE}"
+wget -q "https://github.com/erlang/rebar3/releases/download/${VSN}/${FILE}"
 mkdir -p ${DIR_FOR_BIN}
 chmod +x ${FILE}
 mv ${FILE} ${DIR_FOR_BIN}
diff --git a/dist/install-rebar31 b/dist/install-rebar31
index 686b74d5..ba80ba06 100755
--- a/dist/install-rebar31
+++ b/dist/install-rebar31
@@ -6,9 +6,9 @@ cd "$RUNNER_TEMP"
 
 VSN=${1}
 FILE=rebar3
-DIR_FOR_BIN=.setup-elixir/rebar3
+DIR_FOR_BIN=.setup-elixir/rebar3/bin
 
-wget -q https://github.com/erlang/rebar3/releases/download/"${VSN}"/"${FILE}"
+wget -q "https://github.com/erlang/rebar3/releases/download/${VSN}/${FILE}"
 mkdir -p ${DIR_FOR_BIN}
 chmod +x ${FILE}
 mv ${FILE} ${DIR_FOR_BIN}
diff --git a/src/install-elixir b/src/install-elixir
index 9b7de466..41fb90a8 100755
--- a/src/install-elixir
+++ b/src/install-elixir
@@ -4,7 +4,7 @@ set -eo pipefail
 
 cd "$RUNNER_TEMP"
 
-wget -q https://repo.hex.pm/builds/elixir/"${1}""${2}".zip
-unzip -d .setup-elixir/elixir "${1}""${2}".zip
-rm "${1}""${2}".zip
+wget -q "https://repo.hex.pm/builds/elixir/${1}${2}.zip"
+unzip -d .setup-elixir/elixir "${1}${2}.zip"
+rm -f "${1}${2}.zip"
 echo "$(pwd)/.setup-elixir/elixir/bin" >> "$GITHUB_PATH"
diff --git a/src/install-otp b/src/install-otp
index 175c44a4..d6e55c43 100755
--- a/src/install-otp
+++ b/src/install-otp
@@ -4,9 +4,12 @@ set -eo pipefail
 
 cd "$RUNNER_TEMP"
 
-wget -q -O otp.tar.gz https://repo.hex.pm/builds/otp/"${2}"/"${1}".tar.gz
+OS=${1}
+OTP=${2}
+
+wget -q -O otp.tar.gz "https://repo.hex.pm/builds/otp/${OS}/${OTP}.tar.gz"
 mkdir -p .setup-elixir/otp
 tar zxf otp.tar.gz -C .setup-elixir/otp --strip-components=1
-rm otp.tar.gz
-.setup-elixir/otp/Install -minimal "$(pwd)"/.setup-elixir/otp
+rm -f otp.tar.gz
+.setup-elixir/otp/Install -minimal "$(pwd)/.setup-elixir/otp"
 echo "$(pwd)/.setup-elixir/otp/bin" >> "$GITHUB_PATH"
diff --git a/src/install-rebar3 b/src/install-rebar3
index 686b74d5..ba80ba06 100755
--- a/src/install-rebar3
+++ b/src/install-rebar3
@@ -6,9 +6,9 @@ cd "$RUNNER_TEMP"
 
 VSN=${1}
 FILE=rebar3
-DIR_FOR_BIN=.setup-elixir/rebar3
+DIR_FOR_BIN=.setup-elixir/rebar3/bin
 
-wget -q https://github.com/erlang/rebar3/releases/download/"${VSN}"/"${FILE}"
+wget -q "https://github.com/erlang/rebar3/releases/download/${VSN}/${FILE}"
 mkdir -p ${DIR_FOR_BIN}
 chmod +x ${FILE}
 mv ${FILE} ${DIR_FOR_BIN}
diff --git a/src/installer.js b/src/installer.js
index 9751cbd1..5e799338 100644
--- a/src/installer.js
+++ b/src/installer.js
@@ -4,12 +4,12 @@ const path = require('path')
 /**
  * Install Erlang/OTP.
  *
- * @param {string} version
  * @param {string} osVersion
+ * @param {string} version
  */
-async function installOTP(version, osVersion) {
+async function installOTP(osVersion, version) {
   checkPlatform()
-  await exec(path.join(__dirname, 'install-otp'), [version, osVersion])
+  await exec(path.join(__dirname, 'install-otp'), [osVersion, version])
 }
 
 /**
diff --git a/src/setup-beam.js b/src/setup-beam.js
index 922a07b1..2ea9e52b 100644
--- a/src/setup-beam.js
+++ b/src/setup-beam.js
@@ -28,7 +28,7 @@ async function main() {
 
   // Elixir - optional
   const elixirSpec = getElixirSpecFromInput()
-  if (elixirSpec != undefined) {
+  if (elixirSpec) {
     const [elixirVersion, otpMajor] = await getElixirVersion(
       elixirSpec,
       otpVersion,
@@ -43,7 +43,7 @@ async function main() {
 
   // rebar3 - optional
   const rebar3Spec = getRebar3SpecFromInput()
-  if (rebar3Spec != undefined) {
+  if (rebar3Spec) {
     const rebar3Version = await getRebar3Version(rebar3Spec)
     console.log(`##[group]Installing rebar3 ${rebar3Version}`)
     await installer.installRebar3(rebar3Version)
@@ -51,19 +51,20 @@ async function main() {
     core.setOutput('rebar3-version', otpVersion)
   }
 
-  process.env.PATH = `${process.env.RUNNER_TEMP}/.setup-elixir/otp/bin`
-  process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/elixir/bin`
-  process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/rebar3/bin`
-  process.env.PATH += `:${process.env.PATH}`
-
   // mix - optional
-  let installHex = core.getInput('install-hex')
-  installHex = installHex == null ? 'true' : installHex
-  if (installRebar === 'true') await exec('mix local.rebar --force')
-
-  let installRebar = core.getInput('install-rebar')
-  installRebar = installRebar == null ? 'true' : installRebar
-  if (installHex === 'true') await exec('mix local.hex --force')
+  if (elixirSpec) {
+    process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/otp/bin`
+    process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/elixir/bin`
+    process.env.PATH += `:${process.env.RUNNER_TEMP}/.setup-elixir/rebar3/bin`
+
+    let installRebar = core.getInput('install-rebar')
+    installRebar = installRebar == null ? 'true' : installRebar
+    installRebar && await exec('mix local.rebar --force')
+
+    let installHex = core.getInput('install-hex')
+    installHex = installHex == null ? 'true' : installHex
+    installHex && await exec('mix local.hex --force')
+  }
 }
 
 function getOTPSpecFromInput() {
@@ -78,7 +79,7 @@ function getElixirSpecFromInput() {
   if (process.env.CI_TEST_ENV === 'test') {
     return process.env.CI_TEST_ELIXIR_VSN;
   } else {
-    core.getInput('elixir-version', {required: false}) || undefined;
+    return core.getInput('elixir-version', {required: false});
   }
 }
 
@@ -86,7 +87,7 @@ function getRebar3SpecFromInput() {
   if (process.env.CI_TEST_ENV === 'test') {
     return process.env.CI_TEST_REBAR3_VSN;
   } else {
-    return core.getInput('rebar3-version', {required: false}) || undefined;
+    return core.getInput('rebar3-version', {required: false});
   }
 }
 
@@ -117,8 +118,8 @@ async function getElixirVersion(spec, otpVersion) {
   const gitRef = version ? `v${version}` : spec
   const otpMatch = otpVersion.match(/^OTP-([\.\d]+)/)
 
-  if (otpMatch != null && versions.get(gitRef).includes(otpMatch[0])) {
-    return [gitRef, otpMatch[0]]
+  if (otpMatch && versions.get(gitRef).includes(otpMatch[1])) {
+    return [gitRef, otpMatch[1]]
   } else {
     return [gitRef, null]
   }
@@ -197,7 +198,7 @@ async function getRebar3Version(spec) {
 }
 
 function get(url, testFile) {
-  if (process.env.NODE_ENV === 'test' && testFile !== undefined) {
+  if (process.env.NODE_ENV === 'test' && testFile) {
     return readFile(path.join(__dirname, '..', '__tests__', testFile))
       .then((buf) => buf.toString())
   }