Ignore backup files

diff --git a/.gitignore b/.gitignore
index 96374c4..783d8fd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -17,6 +17,9 @@ $RECYCLE.BIN/
 # Windows shortcuts
 *.lnk

+# Backup files
+*.bak
+
 # =========================
 # Operating System Files
 # =========================