diff --git a/README.md b/README.md
index d9d606b..5baf9a9 100644
--- a/README.md
+++ b/README.md
@@ -14,7 +14,7 @@ You can use this list one of two ways:
 There is a cache_domains.json file to define CDNs and additional meta deta with the following structure
 
 - cache_domains: Array of cache_domain object
-	- name: shortname for the cache domain
+	- name: shortname for the cache domain. Should match `^[0-9A-Za-z]$`
 	- description: a longer description to aid others in identifying what this domain does (not all users of this repo will want to enable all caches)
 	- notes: implementation specific notes which may be useful for other users
 	- mixed_content: true if this domain hosts mixed https and http content (a straight dns injection is unlikely to work in this case). Assumed to be false if undefined
@@ -43,6 +43,7 @@ There is a separate file for each cacheable service. Some notes on formatting:
   - Wildcards are permitted as per below
   - Lines starting with a # will be treated as a comment.
   - Files must end with an empty newline.
+  - File names must match the regular expression `^[0-9A-Za-z].txt`
 
 #### Wildcards
 
diff --git a/cache_domains.json b/cache_domains.json
index 7f16ff2..a408f0c 100644
--- a/cache_domains.json
+++ b/cache_domains.json
@@ -21,9 +21,9 @@
 			"domain_files": ["daybreak.txt"]
 		},
 		{
-			"name": "epic-games",
+			"name": "epicgames",
 			"description": "CDN for Epic Games",
-			"domain_files": ["epic-games.txt"],
+			"domain_files": ["epicgames.txt"],
 			"mixed_content": true
 		},
 		{
diff --git a/epic-games.txt b/epicgames.txt
similarity index 100%
rename from epic-games.txt
rename to epicgames.txt