diff --git a/tag.sh b/tag.sh
index 0db0f28..fbe902c 100755
--- a/tag.sh
+++ b/tag.sh
@@ -59,8 +59,10 @@ listtags() {
     [ -z "$1" ] && fail "No filename supplied."
     FILENAME="$1"
     shift
-    LIMIT="${1:-0}"
 
+    ! file_exists_in_db "$FILENAME" && fail "File '$FILENAME' does not exist in database."
+
+    LIMIT="${1:-0}"
     ADDITIONAL_QUERY=""
     [ $LIMIT -gt 0 ] && ADDITIONAL_QUERY="LIMIT $LIMIT"
 
@@ -145,6 +147,9 @@ add_path() {
     # $PATH1..$PATHN
     TABLE="files"
     COLUMN="filename"
+    for FILE in "$@"; do
+        file_exists_in_db "$FILE" && fail "File '$FILENAME' already exists in database."
+    done
     sqlite_insert_single "$TABLE" "$COLUMN" "$@"
 }
 
@@ -154,8 +159,7 @@ add_hash() {
     COLUMN="fid,md5"
     local FILENAME="${1:-}"
     [ -z "$FILENAME" ] && fail "No file specified."
-    RESULT=$(sqlite_query "SELECT id FROM files WHERE filename = '$FILENAME'")
-    [ -z "$RESULT" ] && fail "File \"$FILENAME\" does not exist in database."
+    ! file_exists_in_db "$FILENAME" && fail "File \"$FILENAME\" does not exist in database."
     sqlite_insert_multi "$TABLE" "$COLUMN" $RESULT "'$2'" 
 }
 
@@ -175,6 +179,17 @@ tag_exists_in_db() {
     fi
 }
 
+file_exists_in_db() {
+    # $FILENAME
+    FILENAME=${1:-}
+    RESULT=$(sqlite_query "SELECT id FROM files WHERE filename = '$FILENAME'")
+    if [[ -z "$RESULT" ]]; then
+        return 1
+    else
+        return 0
+    fi
+}
+
 main() {
 
     [ -z "${1:-}" ] && fail "Usage: tag init/add/import/autoimport/list/listtags"
@@ -219,8 +234,9 @@ main() {
 
     if [[ "$1" = "tag" ]]; then
         shift
-        [ -z "$1" ] && fail "No filename supplied."
+        [ -z "${1:-}" ] && fail "No filename supplied."
         FILENAME="$1"
+        ! file_exists_in_db "$FILENAME" && fail "File '$FILENAME' does not exist in database."
         shift
         [ -z "${1:-}" ] && fail "No tag supplied."
         COUNTER=0