diff --git a/functions/nginx_geo_formatter.py b/functions/nginx_geo_formatter.py
index 3c6a41a..3d8e3c3 100644
--- a/functions/nginx_geo_formatter.py
+++ b/functions/nginx_geo_formatter.py
@@ -4,9 +4,10 @@ import argparse
 
 def format_addresses(addresses: list[dict], args: argparse.Namespace) -> Generator[str, dict, None]:
     # Variables
-    var_name: str = "meta_ip_address"
+    input_var_name: str = args.nginx_geo_input_var
+    output_var_name: str = "meta_ip_address"
 
-    header: str = f"geo ${var_name} \u007b"
+    header: str = f"geo ${input_var_name} ${output_var_name} \u007b"
     footer: str = "\n    default 0;\n}"
     
     yield header
diff --git a/main.py b/main.py
index c2732ec..7f3fc57 100644
--- a/main.py
+++ b/main.py
@@ -72,6 +72,13 @@ if __name__ == "__main__":
                            type=str,
                            help="sudo path (default: %(default)s)")
 
+    argParser.add_argument("--nginx-geo-input-var",
+                           default="http_x_forwarded_for",
+                           const="http_x_forwarded_for",
+                           nargs="?",
+                           type=str,
+                           help="The variable Nginx will read to determine one's real ip address (default: %(default)s)")
+
     args = argParser.parse_args()
 
     addresses: list[dict] = []