diff --git a/bin/tmuxifier b/bin/tmuxifier
index 281182a..0c7d2ca 100755
--- a/bin/tmuxifier
+++ b/bin/tmuxifier
@@ -26,7 +26,7 @@ case "$command" in
   * )
     # Lookup command, attempt to resolve as alias if fails
     ! command_path="$(command -v "tmuxifier-$command")"
-    if [ ! -n $? ]; then
+    if [ -z "$command_path" ]; then
       resolved="$(tmuxifier-alias "$command")"
       if [ ! -z "$resolved" ]; then
         ! command_path="$(command -v "tmuxifier-$resolved")"
diff --git a/libexec/tmuxifier-completions b/libexec/tmuxifier-completions
index e42b981..d9334c3 100755
--- a/libexec/tmuxifier-completions
+++ b/libexec/tmuxifier-completions
@@ -20,7 +20,7 @@ fi
 
 # Lookup command, attempt to resolve as alias if fails
 ! command_path="$(command -v "tmuxifier-$command")"
-if [ ! -n $? ]; then
+if [ -z "$command_path" ]; then
   resolved="$(tmuxifier-alias "$command")"
   if [ ! -z "$resolved" ]; then
     ! command_path="$(command -v "tmuxifier-$resolved")"
diff --git a/libexec/tmuxifier-help b/libexec/tmuxifier-help
index 34e6042..db7b6a8 100755
--- a/libexec/tmuxifier-help
+++ b/libexec/tmuxifier-help
@@ -12,7 +12,7 @@ command="$1"
 
 # Lookup command, attempt to resolve as alias if fails
 ! command_path="$(command -v "tmuxifier-$command")"
-if [ ! -n $? ]; then
+if [ -z "$command_path" ]; then
   resolved="$(tmuxifier-alias "$command")"
   if [ ! -z "$resolved" ]; then
     command="$resolved"