diff --git a/irc/metadata.go b/irc/metadata.go
index a254f280..edb4ce1c 100644
--- a/irc/metadata.go
+++ b/irc/metadata.go
@@ -106,7 +106,7 @@ func syncChannelMetadata(server *Server, rb *ResponseBuffer, channel *Channel) {
 	}
 }
 
-var validMetadataKeyRegexp = regexp.MustCompile("^[A-Za-z0-9_./-]+$")
+var validMetadataKeyRegexp = regexp.MustCompile("^[a-z0-9_./-]+$")
 
 func metadataKeyIsEvil(key string) bool {
 	return !validMetadataKeyRegexp.MatchString(key)
diff --git a/irc/metadata_test.go b/irc/metadata_test.go
index 91de213a..c90dbcec 100644
--- a/irc/metadata_test.go
+++ b/irc/metadata_test.go
@@ -7,9 +7,12 @@ func TestKeyCheck(t *testing.T) {
 		input  string
 		isEvil bool
 	}{
-		{"ImNormal", false},
+		{"ImNormalButIHaveCaps", true},
+		{"imnormalandidonthavecaps", false},
+		{"ergo.chat/vendor-extension", false},
 		{"", true},
 		{":imevil", true},
+		{"im:evil", true},
 		{"key£with$not%allowed^chars", true},
 		{"key.thats_completely/normal-and.fine", false},
 	}