diff --git a/tools/6502_assembler/README.md b/tools/6502_assembler/README.md
index c8842af..f3bdc35 100644
--- a/tools/6502_assembler/README.md
+++ b/tools/6502_assembler/README.md
@@ -1,6 +1,6 @@
 # 6502 Assembler (in a spreadsheet)
 ![!test](6502_assembler.png)
 
-This is proof-of-concept 6502 assembler in a spreadsheet (works with Excel, Libre Office, etc.)
+This is a proof-of-concept 6502 assembler in a spreadsheet (works with Excel, Libre Office, etc.)
 
 The XLSX file is the latest release. Instructions included in the spreadsheet.