diff --git a/main.sh b/main.sh
index c5662ef..898095f 100755
--- a/main.sh
+++ b/main.sh
@@ -4,6 +4,23 @@
 
 set -o errexit  # (-e) exit immediately if any command has a non-zero exit status
 
+# Check if dependencies are installed.
+if ! command -v openssl >/dev/null; then
+  >&2 echo '"openssl" not installed! [required]'
+  exit 1
+fi
+if ! command -v idn >/dev/null; then
+  >&2 echo '"idn" not installed! [required]'
+  exit 1
+fi
+if ! command -v agunua >/dev/null; then
+  >&2 echo '"agunua" not installed! [required]'
+  exit 1
+fi
+if ! command -v torsocks >/dev/null; then
+  >&2 echo '"torsocks" not installed! [optional]'
+fi
+
 # Go where this script is.
 cd "$(dirname "$0")" || exit