diff --git a/create-file-message.sh b/create-file-message.sh
index fcb5ee3..1392b6d 100644
--- a/create-file-message.sh
+++ b/create-file-message.sh
@@ -1,19 +1,23 @@
 #!/bin/env sh
 
 TEMPLATE_FILE="$(dirname "$0")/verify-script.template"
-#echo "template: $TEMPLATE_FILE"
+if [ ! -f "$TEMPLATE_FILE" ]; then
+    echo "'$TEMPLATE_FILE' not found. The template file should have come with this script." 1>&2
+    exit 1
+fi
+
+FILE_PATH="$1"
+if [ ! -f "$FILE_PATH" ]; then
+    echo "'$FILE_PATH' not found" 1>&2
+    exit 1
+fi
+FILE_NAME="$(basename "$FILE_PATH")"
+FILE_HASH="$(sha256sum "$FILE_PATH" | awk '{print $1}')"
 
 # TODO: argument for the message in case you want to apply it to many files.
 read -r -p "Enter message to sign for the file: " MESSAGE
 MESSAGE="$MESSAGE\n"
-#echo "message: $MESSAGE"
-
-FILE_NAME="$(basename "$1")"
-#echo "file name: $FILE_NAME"
-FILE_HASH="$(sha256sum "$FILE_NAME" | awk '{print $1}')"
-#echo "file hash: $FILE_HASH"
 
 SUBSTITUTED_TEMPLATE=$(sed -e "s!{message}!$MESSAGE!g" -e "s!{filename}!$FILE_NAME!g" -e "s!{filehash}!$FILE_HASH!g" "$TEMPLATE_FILE")
 
-#echo "substituted: $SUBSTITUTED_TEMPLATE"
 printf '%s' "$SUBSTITUTED_TEMPLATE" > "$1.sh"
\ No newline at end of file