diff --git a/README.md b/README.md
index fcd054e..b78a100 100644
--- a/README.md
+++ b/README.md
@@ -371,8 +371,9 @@ The following commands will generate a strong passphrase and avoid ambiguous cha
 
 ```console
 export CERTIFY_PASS=$(LC_ALL=C tr -dc 'A-Z1-9' < /dev/urandom | \
-  tr -d "1IOS5U" | fold -w 30 | sed "-es/./ /"{1..26..5} | \
-  cut -c2- | tr " " "-" | head -1) ; printf "\n$CERTIFY_PASS\n\n"
+  tr -d "1IOS5U" | fold -w 30 | sed 's/.\{5\}/& /g' | \
+  cut -c2- | tr " " "-" | head -1 | sed 's/-$//') ; \
+  printf "\n$CERTIFY_PASS\n\n"
 ```
 
 Write the passphrase in a secure location, ideally separate from the portable storage device used for key material, or memorize it.