diff --git a/modules/functions.sh b/modules/functions.sh
index 8ce2fc9..8931232 100644
--- a/modules/functions.sh
+++ b/modules/functions.sh
@@ -3,20 +3,36 @@
 source colors.sh
 
 check_dependencies() {
-	return 0
+	# Usage: check_dependencies 7z unrar curl ...
+	local dependencies=()
+
+	for dependency in "$@"; do
+		if ! command -v "$dependency" >/dev/null; then
+			dependencies+=("$dependency")
+		fi
+	done
+
+	if (( "${#dependencies[@]}" > 0 )); then
+		log_err "Missing dependencies" "${dependencies[@]}"
+		return 1
+	fi
 }
 
-log_info() {
+log() {
+	# Usage: log "NOTICE|ERROR|WARN" this is a log message ...
 	local caller="${0##*/}"
-	echo -e "$caller: INFO: $*" >&2
-}
+	local level="$1"; shift
+	local color
 
-log_notice() {
-	local caller="${0##*/}"
-	echo -e "$caller: ${GREEN}NOTICE: $*${RESET}" >&2
-}
+	case "$level" in
+		NOTICE) color="$GREEN" ;;
+		WARN) color="$YELLOW" ;;
+		ERROR) color="$RED" ;;
 
-log_err() {
-	local caller="${0##*/}"
-	echo -e "$caller: ${RED}ERROR: $*${RESET}" >&2
+		# No color for these levels.
+		INFO) color="" ;;
+		*) color="" ;;
+	esac
+
+	echo -e "$caller: ${color}[$level]: $*${RESET}" >&2
 }