diff --git a/Makefile b/Makefile
index de65729..4d3cda0 100644
--- a/Makefile
+++ b/Makefile
@@ -17,4 +17,4 @@ deinstall:
 	rm -rf $(SHAREDIR)
 
 shellcheck:
-	find bin/ libexec/ -type f -exec shellcheck "{}" \;
+	find bin/ libexec/ -type f -exec shellcheck -x "{}" \;
diff --git a/bin/setup-sourcezap b/bin/setup-sourcezap
index 3e64eb8..23402d3 100755
--- a/bin/setup-sourcezap
+++ b/bin/setup-sourcezap
@@ -8,6 +8,7 @@ libexec="${localbase}"/libexec/sourcezap
 
 ##
 # functions
+# shellcheck source=/dev/null
 . "${libexec}"/functions/print.sh
 
 ##
diff --git a/bin/sourcezap b/bin/sourcezap
index 07da311..ed1e935 100755
--- a/bin/sourcezap
+++ b/bin/sourcezap
@@ -13,6 +13,7 @@ revision="${installdir}"/.sourcezap
 
 ##
 # functions
+# shellcheck source=/dev/null
 . "${libexec}"/functions/print.sh
 
 require_dependency()
diff --git a/libexec/sourcezap/commands/sourcezap-checkout b/libexec/sourcezap/commands/sourcezap-checkout
index 7cc1016..9427427 100755
--- a/libexec/sourcezap/commands/sourcezap-checkout
+++ b/libexec/sourcezap/commands/sourcezap-checkout
@@ -11,6 +11,7 @@ branch=$2
 
 ##
 # functions
+# shellcheck source=/dev/null
 . "${libexec}"/functions/print.sh
 
 ##
diff --git a/libexec/sourcezap/commands/sourcezap-clone b/libexec/sourcezap/commands/sourcezap-clone
index fa7e371..05cab45 100755
--- a/libexec/sourcezap/commands/sourcezap-clone
+++ b/libexec/sourcezap/commands/sourcezap-clone
@@ -12,6 +12,7 @@ branch=$3
 
 ##
 # functions
+# shellcheck source=/dev/null
 . "${libexec}"/functions/print.sh
 
 ##
diff --git a/libexec/sourcezap/commands/sourcezap-install b/libexec/sourcezap/commands/sourcezap-install
index 91c19fa..fed41be 100755
--- a/libexec/sourcezap/commands/sourcezap-install
+++ b/libexec/sourcezap/commands/sourcezap-install
@@ -13,6 +13,7 @@ revfile=$3
 
 ##
 # functions
+# shellcheck source=/dev/null
 . "${libexec}"/functions/print.sh
 
 perform_update()
diff --git a/libexec/sourcezap/commands/sourcezap-pull b/libexec/sourcezap/commands/sourcezap-pull
index 5ee9f53..51c527a 100755
--- a/libexec/sourcezap/commands/sourcezap-pull
+++ b/libexec/sourcezap/commands/sourcezap-pull
@@ -10,6 +10,7 @@ gitdir=$1
 
 ##
 # functions
+# shellcheck source=/dev/null
 . "${libexec}"/functions/print.sh
 
 ##
diff --git a/libexec/sourcezap/commands/sourcezap-rm b/libexec/sourcezap/commands/sourcezap-rm
index 21ce4e3..1fb53de 100755
--- a/libexec/sourcezap/commands/sourcezap-rm
+++ b/libexec/sourcezap/commands/sourcezap-rm
@@ -10,6 +10,7 @@ installdir=$2
 
 ##
 # functions
+# shellcheck source=/dev/null
 . "${libexec}"/functions/print.sh
 
 erase()
diff --git a/libexec/sourcezap/setup/setup-user b/libexec/sourcezap/setup/setup-user
index ab90656..4c0619a 100755
--- a/libexec/sourcezap/setup/setup-user
+++ b/libexec/sourcezap/setup/setup-user
@@ -16,7 +16,7 @@ user="_sourcezap"
 if id -u "${user}" > /dev/null 2>&1; then
    printok "${user} user exists"
 else
-    pw useradd
+    pw useradd \
        -n "${user}" \
        -c "sourcezap user" \
        -m \