diff --git a/giteainstall b/giteainstall
index 8e9e129..99ce9aa 100755
--- a/giteainstall
+++ b/giteainstall
@@ -84,15 +84,6 @@ usage() {
     printf -- "  -h | -help | --help   Show this help screen\n\n"
 }
 
-#
-# Function inputcheck
-#
-inputcheck () {
-    [[ -z "$hostname" ]] && { usage; echo "ERROR: DOMAIN CANNOT BE EMPTY!"; exit 1; }
-    [[ "$hostname" =~ [[:space:]/] ]] && { echo "ERROR: DOMAIN INVALID (no spaces or slashes allowed)"; exit 1; }
-    [[ -z "$dbpass" ]] && { usage; echo "ERROR: DATABASE PASSWORD CANNOT BE EMPTY!"; exit 1; }
-}
-
 #
 # Let's go
 #
@@ -116,7 +107,57 @@ while getopts "n:p:m:a:h" option; do
     esac
 done
 
-inputcheck "$hostname" "$dbpass"
+#
+# Parse and validate input
+#
+if [[ -z "$hostname" || -z "$dbpass" ]]; then
+    usage
+    printf "\nERROR: Both -n (domain) and -p (database password) are required.\n\n"
+    exit 1
+fi
+
+# Convert to lowercase (domains are case-insensitive)
+hostname=$(echo "$hostname" | tr '[:upper:]' '[:lower:]')
+
+# Disallow leading hyphen (breaks getopts and invalid by RFC)
+if [[ "$hostname" =~ ^- ]]; then
+    printf "\nERROR: Domain cannot start with a hyphen.\n"
+    printf "Example of valid input: git1.example.com\n\n"
+    exit 1
+fi
+
+# Disallow spaces, slashes, underscores
+if [[ "$hostname" =~ [[:space:]/_] ]]; then
+    printf "\nERROR: Domain cannot contain spaces, slashes, or underscores.\n\n"
+    exit 1
+fi
+
+# Validate domain format (RFC 1123)
+if [[ ! "$hostname" =~ ^([a-z0-9]+(-[a-z0-9]+)*\.)+[a-z]{2,}$ ]]; then
+    printf "\nERROR: Invalid domain format.\n"
+    printf "Example of valid input: git1.example.com\n\n"
+    exit 1
+fi
+
+# Check for spaces in DB credentials
+if [[ "$dbpass" =~ [[:space:]] ]]; then
+    printf "\nERROR: Database password cannot contain spaces.\n\n"
+    exit 1
+fi
+
+# Prevent accidental overwrite of existing Nginx config
+if [[ -f "/etc/nginx/conf.d/${hostname}.conf" ]]; then
+    printf "\nERROR: A configuration file already exists for %s.\n" "$hostname"
+    printf "Refusing to overwrite existing site.\n\n"
+    exit 1
+fi
+
+# Check for existing references in other Nginx configs
+hostcheck=$(grep -r --exclude="README.md" "$hostname" /etc/nginx/ 2>/dev/null || true)
+if [[ -n "$hostcheck" ]]; then
+    printf "\nFound existing configuration mentioning %s — aborting to avoid collision.\n\n" "$hostname"
+    exit 1
+fi
 
 #
 # Check for the latest Gitea version
@@ -125,12 +166,6 @@ version=$(curl -s "https://dl.gitea.com/gitea/version.json" | grep -oP '"version
 if [[ -z "$version" ]]; then printf "Could not determine latest version. Falling back to version %s\n\n" "$fallbackversion" ; version="$fallbackversion" ; fi
 printf "\nUsing Gitea version: %s\n" "$version"
 
-#
-# Check for existing Nginx host file with same domain
-#
-hostcheck=$(grep -r --exclude="giteainstall" --exclude="postinstall" --exclude="README.md" "$hostname" /etc/nginx/ 2>/dev/null || true)
-if [[ -n "$hostcheck" ]]; then printf "\nFound existing configuration mentioning %s — aborting to avoid collision.\n\n" "$hostname" ; exit 1 ; fi
-
 #
 # Create Gitea counter logic
 #