diff --git a/viper.go b/viper.go
index 6c249fe..b23d837 100644
--- a/viper.go
+++ b/viper.go
@@ -174,7 +174,7 @@
 }
 
 // Universally supported extensions.
-var SupportedExts []string = []string{"json", "toml", "yaml", "yml"}
+var SupportedExts []string = []string{"json", "toml", "yaml", "yml", "properties", "props", "prop"}
 
 // Universally supported remote providers.
 var SupportedRemoteProviders []string = []string{"etcd", "consul"}