diff --git a/erpnext/regional/india/utils.py b/erpnext/regional/india/utils.py
index aad998b..5295605 100644
--- a/erpnext/regional/india/utils.py
+++ b/erpnext/regional/india/utils.py
@@ -11,7 +11,7 @@
 	if doc.gstin:
 		doc.gstin = doc.gstin.upper()
 		if doc.gstin not in ["NA", "na"]:
-			p = re.compile("[0-9]{2}[a-zA-Z]{4}[0-9a-zA-Z]{1}[0-9]{4}[a-zA-Z]{1}[1-9a-zA-Z]{1}[0-9a-zA-Z]{1}[0-9a-zA-Z]{1}")
+			p = re.compile("[0-9]{2}[A-Z]{4}[0-9A-Z]{1}[0-9]{4}[A-Z]{1}[1-9A-Z]{1}[0-9A-Z]{1}[0-9A-Z]{1}")
 			if not p.match(doc.gstin):
 				frappe.throw(_("Invalid GSTIN or Enter NA for Unregistered"))