diff --git a/README.md b/README.md
index 0eb7e1a..02b7f66 100644
--- a/README.md
+++ b/README.md
@@ -77,26 +77,26 @@ The avatar directory could look like this:
 
 Configuration is done through environment variables.
 
-#### LIBRAVATARSERV_DIR
+**LIBRAVATARSERV_DIR**
 
 The directory containing the avatars.
 
 Default: empty
 
-#### LIBRAVATARSERV_DEFAULT_FALLBACK
+**LIBRAVATARSERV_DEFAULT_FALLBACK**
 
 Controls what happens if no fallback was requested.
 
 Default: 404
 
-#### LIBRAVATARSERV_REDIRECT_NOFALLBACK
+**LIBRAVATARSERV_REDIRECT_NOFALLBACK**
 
 Set to 1 to redirect to libravatar.org if the requested fallback is not
 supported.
 
 Default: 0
 
-#### LIBRAVATARSERV_REDIRECT_NOUSER
+**LIBRAVATARSERV_REDIRECT_NOUSER**
 
 Set to 1 to redirect to libravatar.org if the user is not found.