diff --git a/Makefile b/Makefile
index 8de8b368..2131fe3d 100644
--- a/Makefile
+++ b/Makefile
@@ -65,7 +65,7 @@ lint-shell:
 	docker run \
 		--volume="$${PWD}:/code" \
 		-w /code \
-		-e SHELLCHECK_OPTS='-s bash -S warning -a' \
+		-e SHELLCHECK_OPTS='-s bash -S style -a' \
 		--rm koalaman/shellcheck \
 		$$(find src .ci utils tests docs -type f \
 			-name '*.sh' -o -name '*.bash' -o -name '*.bats')
diff --git a/docs/build.sh b/docs/build.sh
index 529a48bd..7b4c8013 100644
--- a/docs/build.sh
+++ b/docs/build.sh
@@ -29,7 +29,7 @@ function copy_to_posts {
   current_date=$(date "+%Y-%m-%d")
 
   # Creating command refernce:
-  for com in $MAN_LOCATION/git-secret-*.1.md; do
+  for com in "$MAN_LOCATION"/git-secret-*.1.md; do
     local short_name
     short_name=$(echo "$com" | sed -n "s|$MAN_LOCATION/\(.*\)\.1\.md|\1|p")
     local command_header="---
@@ -69,7 +69,7 @@ function copy_install_scripts {
 
 
 function copy_version {
-   echo "$(./git-secret --version)" > docs/_includes/version.txt
+   ./git-secret --version > docs/_includes/version.txt
 }
 
 
diff --git a/src/_utils/_git_secret_tools.sh b/src/_utils/_git_secret_tools.sh
index 82921b27..86675890 100644
--- a/src/_utils/_git_secret_tools.sh
+++ b/src/_utils/_git_secret_tools.sh
@@ -388,7 +388,7 @@ function _append_relative_root_path {
 
   local subdir
   subdir=$(git rev-parse --show-prefix)   # get the subdir of repo, like "subdir/"
-  if [ ! -z "$subdir" ]; then
+  if [ -n "$subdir" ]; then
     full_path="$(dirname "$full_path")/${subdir}/$(basename "$full_path")"
   fi
 
diff --git a/tests/test_cat.bats b/tests/test_cat.bats
index 9f967b0a..f39b4ab8 100644
--- a/tests/test_cat.bats
+++ b/tests/test_cat.bats
@@ -1,4 +1,6 @@
 #!/usr/bin/env bats
+# shellcheck disable=SC2030,SC2031
+# above is to avoid shellcheck info warnings that we don't understand
 
 load _test_base
 
@@ -71,16 +73,17 @@ function teardown {
   mkdir subdir
   echo "content2" > subdir/new_filename.txt
 
-  cd subdir
-  run git secret add new_filename.txt
-  [ "$status" -eq 0 ]
-  run git secret hide
-  [ "$status" -eq 0 ]
+  ( # start subshell for subdir tests
+    cd subdir
+    run git secret add new_filename.txt
+    [ "$status" -eq 0 ]
+    run git secret hide
+    [ "$status" -eq 0 ]
 
-  run git secret cat -d "$TEST_GPG_HOMEDIR" -p "$password" new_filename.txt
-  [ "$status" -eq 0 ]
+    run git secret cat -d "$TEST_GPG_HOMEDIR" -p "$password" new_filename.txt
+    [ "$status" -eq 0 ]
+  ) # end subshell, cd back up
 
   # clean up
-  cd ..
   rm -rf subdir
 }
diff --git a/tests/test_hide.bats b/tests/test_hide.bats
index ff766b26..af3378a4 100644
--- a/tests/test_hide.bats
+++ b/tests/test_hide.bats
@@ -42,7 +42,7 @@ function teardown {
   # File must be a binary:
   local mime
   mime="$(file --mime-type --mime-encoding "$new_file" | grep 'charset=binary')"
-  [ ! -z "$mime" ]
+  [ -n "$mime" ]
 }
 
 
@@ -61,7 +61,7 @@ function teardown {
   # File must be a text:
   local mime
   mime="$(file --mime-type --mime-encoding "$new_file" | grep 'charset=us-ascii')"
-  [ ! -z "$mime" ]
+  [ -n "$mime" ]
 }
 
 
@@ -129,15 +129,17 @@ function teardown {
   # Verify that the second file is there:
   [ -f "$second_file" ]
 
-  # cd into the subdir
-  cd "$root_dir"
+  ( # start subshell for following commands
 
-  # Now it should hide 2 files:
-  run git secret hide
-  [ "$status" -eq 0 ]
+    # cd into the subdir
+    cd "$root_dir"
+
+    # Now it should hide 2 files:
+    run git secret hide
+    [ "$status" -eq 0 ]
+  ) # end subshell, return to ..
 
-  # cd back and clean up
-  cd ".."
+  # clean up
   rm -rf "$root_dir"
 }
 
diff --git a/tests/test_removeperson.bats b/tests/test_removeperson.bats
index 64f03cae..abd7045d 100644
--- a/tests/test_removeperson.bats
+++ b/tests/test_removeperson.bats
@@ -27,6 +27,8 @@ function teardown {
 
 @test "run 'removeperson' with short name" {
   local name
+  # don't complain about sed
+  # shellcheck disable=SC2001 
   name=$(echo "$TEST_DEFAULT_USER" | sed -e 's/@.*//')
 
   # removeperson must use full email, not short name
diff --git a/tests/test_reveal.bats b/tests/test_reveal.bats
index 8191963f..006c5273 100644
--- a/tests/test_reveal.bats
+++ b/tests/test_reveal.bats
@@ -278,16 +278,17 @@ function teardown {
   mkdir subdir
   echo "content2" > subdir/new_filename.txt
 
-  cd subdir
-  run git secret add new_filename.txt
-  [ "$status" -eq 0 ]
-  run git secret hide
-  [ "$status" -eq 0 ]
-
-  run git secret reveal -d "$TEST_GPG_HOMEDIR" -p "$password" new_filename.txt
-  [ "$status" -eq 0 ]
+  ( # start subshell for subdir tests
+    cd subdir
+    run git secret add new_filename.txt
+    [ "$status" -eq 0 ]
+    run git secret hide
+    [ "$status" -eq 0 ]
+  
+    run git secret reveal -d "$TEST_GPG_HOMEDIR" -p "$password" new_filename.txt
+    [ "$status" -eq 0 ]
+  ) # end subshell
 
   # clean up
-  cd ..
   rm -rf subdir
 }
diff --git a/tests/test_tell.bats b/tests/test_tell.bats
index 6609d814..21f598c5 100644
--- a/tests/test_tell.bats
+++ b/tests/test_tell.bats
@@ -199,6 +199,8 @@ function teardown {
   install_fixture_key "$TEST_NOEMAIL_COMMENT_USER"
 
   local name
+  # don't complain about sed
+  # shellcheck disable=SC2001 
   name=$(echo "$TEST_NOEMAIL_COMMENT_USER" | sed -e 's/@.*//')
   # echo "$name" | sed "s/^/# '$BATS_TEST_DESCRIPTION' name is: /" >&3