diff --git a/lib/dpl/provider/atlas.rb b/lib/dpl/provider/atlas.rb
index c51d6d707..198649f09 100644
--- a/lib/dpl/provider/atlas.rb
+++ b/lib/dpl/provider/atlas.rb
@@ -16,7 +16,7 @@ class Atlas < Provider
             chmod +x $HOME/bin/gimme
           fi
 
-          if [ -z $GOPATH ]; then
+          if [ -z "$GOPATH" ]; then
             export GOPATH="$HOME/gopath"
           else
             export GOPATH="$HOME/gopath:$GOPATH"
diff --git a/lib/dpl/provider/pypi.rb b/lib/dpl/provider/pypi.rb
index 0e72c5f2e..6b73e8056 100644
--- a/lib/dpl/provider/pypi.rb
+++ b/lib/dpl/provider/pypi.rb
@@ -68,7 +68,7 @@ def pypi_wheel_arg
       def install_deploy_dependencies
         # --user likely fails inside virtualenvs but is needed outside to avoid needing sudo.
         # `--upgrade-strategy eager` prevents the old resolver from keeping an outdated dependency if it's preinstalled
-        unless context.shell "if [ -z ${VIRTUAL_ENV+x} ]; then export PIP_USER=yes; fi && " \
+        unless context.shell "if [ -z \"${VIRTUAL_ENV}\" ]; then export PIP_USER=yes; fi && " \
                              "wget -nv -O - https://bootstrap.pypa.io/get-pip.py | python - --no-setuptools --no-wheel && " \
                              "pip install --upgrade --upgrade-strategy eager #{pypi_setuptools_arg} #{pypi_twine_arg} #{pypi_wheel_arg}"
           error "Couldn't install pip, setuptools, twine or wheel."
diff --git a/spec/provider/pypi_spec.rb b/spec/provider/pypi_spec.rb
index a9588522d..5e93ae0f8 100644
--- a/spec/provider/pypi_spec.rb
+++ b/spec/provider/pypi_spec.rb
@@ -9,7 +9,7 @@
   describe "#install_deploy_dependencies" do
     example do
       expect(provider.context).to receive(:shell).with(
-        "if [ -z ${VIRTUAL_ENV+x} ]; then export PIP_USER=yes; fi && wget -nv -O - https://bootstrap.pypa.io/get-pip.py | python - --no-setuptools --no-wheel && pip install --upgrade --upgrade-strategy eager setuptools twine wheel"
+        "if [ -z \"${VIRTUAL_ENV}\" ]; then export PIP_USER=yes; fi && wget -nv -O - https://bootstrap.pypa.io/get-pip.py | python - --no-setuptools --no-wheel && pip install --upgrade --upgrade-strategy eager setuptools twine wheel"
       ).and_return(true)
       provider.install_deploy_dependencies
     end
@@ -21,7 +21,7 @@
       provider.options.update(:twine_version => '1.1.0')
       provider.options.update(:wheel_version => '0.1.0')
       expect(provider.context).to receive(:shell).with(
-        "if [ -z ${VIRTUAL_ENV+x} ]; then export PIP_USER=yes; fi && wget -nv -O - https://bootstrap.pypa.io/get-pip.py | python - --no-setuptools --no-wheel && pip install --upgrade --upgrade-strategy eager setuptools==1.0.1 twine==1.1.0 wheel==0.1.0"
+        "if [ -z \"${VIRTUAL_ENV}\" ]; then export PIP_USER=yes; fi && wget -nv -O - https://bootstrap.pypa.io/get-pip.py | python - --no-setuptools --no-wheel && pip install --upgrade --upgrade-strategy eager setuptools==1.0.1 twine==1.1.0 wheel==0.1.0"
       ).and_return(true)
       provider.install_deploy_dependencies
     end