diff --git a/cryptfs/gcm_go14.go b/cryptfs/gcm_go1.4.go
similarity index 96%
rename from cryptfs/gcm_go14.go
rename to cryptfs/gcm_go1.4.go
index 0d4d5a6..0a2ff49 100644
--- a/cryptfs/gcm_go14.go
+++ b/cryptfs/gcm_go1.4.go
@@ -1,4 +1,5 @@
 // +build !go1.5
+// = go 1.4 or lower
 
 package cryptfs
 
diff --git a/cryptfs/gcm_go15.go b/cryptfs/gcm_go1.5.go
similarity index 95%
rename from cryptfs/gcm_go15.go
rename to cryptfs/gcm_go1.5.go
index 3a8055e..c469357 100644
--- a/cryptfs/gcm_go15.go
+++ b/cryptfs/gcm_go1.5.go
@@ -1,4 +1,5 @@
 // +build go1.5
+// = go 1.5 or higher
 
 package cryptfs