diff --git a/.gitignore b/.gitignore
index a7dfef2..4e09d79 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,6 +8,7 @@ doc/kristall.1
 *~
 *.autosave
 *.a
+*.bak
 *.core
 *.moc
 *.o
diff --git a/doc/gen-man.sh b/doc/gen-man.sh
index 8391c73..4463c5a 100755
--- a/doc/gen-man.sh
+++ b/doc/gen-man.sh
@@ -46,7 +46,7 @@ cp "$man_head" "$man_output"
 
 # Insert last modified date (use last-modified date of help.gemini)
 last_modified=$(date -r "$gemtext_in" +"%F")
-sed -i "$man_output" -e 's#\$(DATE)#'"$last_modified"'#g'
+sed -i'.bak' -e 's#\$(DATE)#'"$last_modified"'#g' "$man_output"
 
 # Some pre-processing before giving our gemtext to the awk script.
 gem_in=$(