diff --git a/lib/gen-version-script.sh b/lib/gen-version-script.sh
index e753eaf5..ec801966 100644
--- a/lib/gen-version-script.sh
+++ b/lib/gen-version-script.sh
@@ -23,5 +23,5 @@ while read sym; do
 	    ;;
     esac
 done
-sed  -n 's/^\s*\(notmuch_[a-z_]*\)\s*(.*/\t\1;/p' $HEADER
+sed  -n 's/^[[:space:]]*\(notmuch_[a-z_]*\)[[:space:]]*(.*/ \1;/p' $HEADER
 printf "local: *;\n};\n"