diff --git a/modules/git/functions/git-commit-lost b/modules/git/functions/git-commit-lost
index ef7c5ac..e801e6d 100644
--- a/modules/git/functions/git-commit-lost
+++ b/modules/git/functions/git-commit-lost
@@ -1,19 +1,12 @@
-#
-# Lists lost Git commits.
-#
-# Authors:
-#   Sorin Ionescu <sorin.ionescu@gmail.com>
-#
-
-if ! is-true "$(git rev-parse --is-inside-work-tree 2> /dev/null)"; then
+if ! is-true "$(commmand git rev-parse --is-inside-work-tree 2> /dev/null)"; then
   print "${0}: not a repository work tree: ${PWD}" >&2
   return 1
 fi
 
-git fsck 2> /dev/null \
+command git fsck 2> /dev/null \
   | grep "^dangling commit" \
   | awk '{print $3}' \
-  | git log \
+  | command git log \
       --date-order \
       --no-walk \
       --stdin \
diff --git a/modules/git/functions/git-dir b/modules/git/functions/git-dir
index 429ae25..215c849 100644
--- a/modules/git/functions/git-dir
+++ b/modules/git/functions/git-dir
@@ -1,11 +1,4 @@
-#
-# Displays the path to the Git directory.
-#
-# Authors:
-#   Sorin Ionescu <sorin.ionescu@gmail.com>
-#
-
-local git_dir="${$(git rev-parse --git-dir):A}"
+local git_dir="${$(command git rev-parse --git-dir):A}"
 
 if [[ -n "${git_dir}" ]]; then
   print "${git_dir}"
diff --git a/modules/git/functions/git-ignore-add b/modules/git/functions/git-ignore-add
index bd16c01..bb05ab8 100644
--- a/modules/git/functions/git-ignore-add
+++ b/modules/git/functions/git-ignore-add
@@ -1,10 +1,3 @@
-#
-# Adds files passed as parameters to .gitignore in project root
-#
-# Authors:
-#   Matt Hamilton <m@tthamilton.com>
-#
-
 # make sure we have a git-root
 if ! git-root &> /dev/null; then
   print 'not in a git repository' >&2
diff --git a/modules/git/functions/git-root b/modules/git/functions/git-root
index a68f9f6..7ed44ff 100644
--- a/modules/git/functions/git-root
+++ b/modules/git/functions/git-root
@@ -1,11 +1,4 @@
-#
-# Displays the path to the working tree root.
-#
-# Authors:
-#   Sorin Ionescu <sorin.ionescu@gmail.com>
-#
-
-local root="$(git rev-parse --show-toplevel 2> /dev/null)"
+local root="$(command git rev-parse --show-toplevel 2> /dev/null)"
 
 if [[ -n "${root}" ]]; then
   print "${root}"
diff --git a/modules/git/functions/git-stash-clear-interactive b/modules/git/functions/git-stash-clear-interactive
index a2ad7dc..0197be9 100644
--- a/modules/git/functions/git-stash-clear-interactive
+++ b/modules/git/functions/git-stash-clear-interactive
@@ -1,11 +1,4 @@
-#
-# Asks for confirmation before clearing the Git stash.
-#
-# Authors:
-#   Sorin Ionescu <sorin.ionescu@gmail.com>
-#
-
-if ! is-true "$(git rev-parse --is-inside-work-tree 2> /dev/null)"; then
+if ! is-true "$(command git rev-parse --is-inside-work-tree 2> /dev/null)"; then
   print "${0}: not a repository work tree: ${PWD}" >&2
   return 1
 fi
@@ -13,10 +6,10 @@ fi
 local stashed
 
 if [[ -f "$(git-dir)/refs/stash" ]]; then
-  stashed="$(git stash list 2> /dev/null | wc -l | awk '{print $1}')"
+  stashed="$(command git stash list 2> /dev/null | wc -l | awk '{print $1}')"
   if (( ${stashed} > 0 )); then
     if read -q "?Clear ${stashed} stashed state(s) [y/N]? "; then
-      git stash clear
+      command git stash clear
     fi
   fi
 fi
diff --git a/modules/git/functions/git-stash-dropped b/modules/git/functions/git-stash-dropped
index 2fabed9..1cc979b 100644
--- a/modules/git/functions/git-stash-dropped
+++ b/modules/git/functions/git-stash-dropped
@@ -1,19 +1,12 @@
-#
-# Lists dropped Git stashed states.
-#
-# Authors:
-#   Sorin Ionescu <sorin.ionescu@gmail.com>
-#
-
-if ! is-true "$(git rev-parse --is-inside-work-tree 2> /dev/null)"; then
+if ! is-true "$(command git rev-parse --is-inside-work-tree 2> /dev/null)"; then
   print "${0}: not a repository work tree: ${PWD}" >&2
   return 1
 fi
 
-git fsck --unreachable 2> /dev/null \
+command git fsck --unreachable 2> /dev/null \
   | grep 'commit' \
   | awk '{print $3}' \
-  | git log \
+  | command git log \
       --pretty=format:${_git_log_oneline_format} \
       --extended-regexp \
       --grep="${1:-(WIP )?[Oo]n [^:]+:}" \
diff --git a/modules/git/functions/git-stash-recover b/modules/git/functions/git-stash-recover
index 1f1916d..8b5adec 100644
--- a/modules/git/functions/git-stash-recover
+++ b/modules/git/functions/git-stash-recover
@@ -1,11 +1,4 @@
-#
-# Recovers dropped Git stashed states.
-#
-# Authors:
-#   Sorin Ionescu <sorin.ionescu@gmail.com>
-#
-
-if ! is-true "$(git rev-parse --is-inside-work-tree 2> /dev/null)"; then
+if ! is-true "$(command git rev-parse --is-inside-work-tree 2> /dev/null)"; then
   print "${0}: not a repository work tree: ${PWD}" >&2
   return 1
 fi
@@ -14,5 +7,5 @@ local commit
 
 for commit in "${@}"; do
   git update-ref \
-    -m "$(git log -1 --pretty="format:%s" "$commit")" refs/stash "${commit}"
+    -m "$(command git log -1 --pretty="format:%s" "$commit")" refs/stash "${commit}"
 done
diff --git a/modules/git/functions/git-submodule-move b/modules/git/functions/git-submodule-move
index d2d5ae4..2f7132c 100644
--- a/modules/git/functions/git-submodule-move
+++ b/modules/git/functions/git-submodule-move
@@ -1,11 +1,4 @@
-#
-# Moves a Git submodule.
-#
-# Authors:
-#   Sorin Ionescu <sorin.ionescu@gmail.com>
-#
-
-if ! is-true "$(git rev-parse --is-inside-work-tree 2> /dev/null)"; then
+if ! is-true "$(command git rev-parse --is-inside-work-tree 2> /dev/null)"; then
   print "${0}: not a repository work tree: ${PWD}" >&2
   return 1
 elif [[ "${PWD}" != "$(git-root)" ]]; then
@@ -17,7 +10,7 @@ local src="${1}"
 local dst="${2}"
 local url
 
-url="$(git config --file "$(git-root)/.gitmodules" --get "submodule.${src}.url")"
+url="$(command git config --file "$(git-root)/.gitmodules" --get "submodule.${src}.url")"
 
 if [[ -z "${url}" ]]; then
   print "${0}: submodule not found: ${src}" >&2
diff --git a/modules/git/functions/git-submodule-remove b/modules/git/functions/git-submodule-remove
index 51c214b..033d39a 100644
--- a/modules/git/functions/git-submodule-remove
+++ b/modules/git/functions/git-submodule-remove
@@ -1,26 +1,19 @@
-#
-# Removes a Git submodule.
-#
-# Authors:
-#   Sorin Ionescu <sorin.ionescu@gmail.com>
-#
-
-if ! is-true "$(git rev-parse --is-inside-work-tree 2> /dev/null)"; then
+if ! is-true "$(command git rev-parse --is-inside-work-tree 2> /dev/null)"; then
   print "${0}: not a repository work tree: ${PWD}" >&2
   return 1
 elif [[ "${PWD}" != "$(git-root)" ]]; then
   print "${0}: must be run from the root of the work tree" >&2
   return 1
-elif ! git config --file .gitmodules --get "submodule.${1}.path" &>/dev/null; then
+elif ! command git config --file .gitmodules --get "submodule.${1}.path" &>/dev/null; then
   print "${0}: submodule not found: ${1}" >&2
   return 1
 fi
 
-git config --file "$(git-dir)/config" --remove-section "submodule.${1}" &>/dev/null
-git config --file "$(git-root)/.gitmodules" --remove-section "submodule.${1}" &>/dev/null
-git add .gitmodules
+command git config --file "$(git-dir)/config" --remove-section "submodule.${1}" &>/dev/null
+command git config --file "$(git-root)/.gitmodules" --remove-section "submodule.${1}" &>/dev/null
+command git add .gitmodules
 
-git rm --cached -rf "${1}"
+command git rm --cached -rf "${1}"
 rm -rf "${1}"
 rm -rf "$(git-dir)/modules/${1}"
 
diff --git a/modules/git/functions/is-true b/modules/git/functions/is-true
new file mode 100644
index 0000000..e56f2bb
--- /dev/null
+++ b/modules/git/functions/is-true
@@ -0,0 +1,5 @@
+# Checks a boolean variable for "true".
+# Case insensitive: "1", "y", "yes", "t", "true", "o", and "on".
+is-true() {
+  [[ -n "$1" && "$1" == (1|[Yy]([Ee][Ss]|)|[Tt]([Rr][Uu][Ee]|)|[Oo]([Nn]|)) ]]
+}