diff --git a/tools/build_test_env.sh b/tools/build_test_env.sh
index 9788d5752..c824107f6 100755
--- a/tools/build_test_env.sh
+++ b/tools/build_test_env.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 # Copyright (C) 2016 Gauvain Pocentek <gauvain@pocentek.net>
 #
 # This program is free software: you can redistribute it and/or modify
@@ -71,7 +71,7 @@ CONFIG=/tmp/python-gitlab.cfg
 GITLAB() { gitlab --config-file "$CONFIG" "$@"; }
 GREEN='\033[0;32m'
 NC='\033[0m'
-OK() { echo -e "${GREEN}OK${NC}"; }
+OK() { printf "${GREEN}OK${NC}\\n"; }
 
 log "Waiting for gitlab to come online... "
 I=0
@@ -81,7 +81,7 @@ while :; do
     sleep 4
     curl -s http://localhost:8080/users/sign_in 2>/dev/null \
         | grep -q "GitLab Community Edition" && break
-    let I=I+5
+    I=$((I+5))
     [ "$I" -eq 120 ] && exit 1
 done
 sleep 5
diff --git a/tools/functional_tests.sh b/tools/functional_tests.sh
index cf9c63239..2ad0219d9 100755
--- a/tools/functional_tests.sh
+++ b/tools/functional_tests.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 # Copyright (C) 2015 Gauvain Pocentek <gauvain@pocentek.net>
 #
 # This program is free software: you can redistribute it and/or modify
@@ -20,61 +20,61 @@ BUILD_TEST_ENV_AUTO_CLEANUP=true
 
 set -e
 
-echo -n "Testing project creation... "
+printf %s "Testing project creation... "
 PROJECT_ID=$(GITLAB project create --name test-project1 \
     | grep ^id: | cut -d' ' -f2)
 GITLAB project list | grep -q test-project1
 OK
 
-echo -n "Testing project update... "
+printf %s "Testing project update... "
 GITLAB project update --id "$PROJECT_ID" --description "My New Description"
 OK
 
-echo -n "Testing user creation... "
+printf %s "Testing user creation... "
 USER_ID=$(GITLAB user create --email fake@email.com --username user1 \
     --name "User One" --password fakepassword | grep ^id: | cut -d' ' -f2)
 OK
 
-echo -n "Testing verbose output... "
+printf %s "Testing verbose output... "
 GITLAB -v user list | grep -q avatar-url
 OK
 
-echo -n "Testing CLI args not in output... "
+printf %s "Testing CLI args not in output... "
 GITLAB -v user list | grep -qv config-file
 OK
 
-echo -n "Testing adding member to a project... "
+printf %s "Testing adding member to a project... "
 GITLAB project-member create --project-id "$PROJECT_ID" \
     --user-id "$USER_ID" --access-level 40 >/dev/null 2>&1
 OK
 
-echo -n "Testing file creation... "
+printf %s "Testing file creation... "
 GITLAB project-file create --project-id "$PROJECT_ID" \
     --file-path README --branch-name master --content "CONTENT" \
     --commit-message "Initial commit" >/dev/null 2>&1
 OK
 
-echo -n "Testing issue creation... "
+printf %s "Testing issue creation... "
 ISSUE_ID=$(GITLAB project-issue create --project-id "$PROJECT_ID" \
     --title "my issue" --description "my issue description" \
     | grep ^id: | cut -d' ' -f2)
 OK
 
-echo -n "Testing note creation... "
+printf %s "Testing note creation... "
 GITLAB project-issue-note create --project-id "$PROJECT_ID" \
     --issue-id "$ISSUE_ID" --body "the body" >/dev/null 2>&1
 OK
 
-echo -n "Testing branch creation... "
+printf %s "Testing branch creation... "
 GITLAB project-branch create --project-id "$PROJECT_ID" \
     --branch-name branch1 --ref master >/dev/null 2>&1
 OK
 
-echo -n "Testing branch deletion... "
+printf %s "Testing branch deletion... "
 GITLAB project-branch delete --project-id "$PROJECT_ID" \
     --name branch1 >/dev/null 2>&1
 OK
 
-echo -n "Testing project deletion... "
+printf %s "Testing project deletion... "
 GITLAB project delete --id "$PROJECT_ID"
 OK
diff --git a/tools/py_functional_tests.sh b/tools/py_functional_tests.sh
index b6e95971e..4538541fa 100755
--- a/tools/py_functional_tests.sh
+++ b/tools/py_functional_tests.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 # Copyright (C) 2015 Gauvain Pocentek <gauvain@pocentek.net>
 #
 # This program is free software: you can redistribute it and/or modify