EXTF must be in quotes
diff --git a/erpnext/regional/report/datev/datev.py b/erpnext/regional/report/datev/datev.py
index bd70639..0b0bb76 100644
--- a/erpnext/regional/report/datev/datev.py
+++ b/erpnext/regional/report/datev/datev.py
@@ -282,7 +282,7 @@
 		# A = DATEV format
 		#   DTVF = created by DATEV software,
 		#   EXTF = created by other software
-		"EXTF",
+		'"EXTF"',
 		# B = version of the DATEV format
 		#   141 = 1.41, 
 		#   510 = 5.10,