diff --git a/internal/config/config_validation_internal_test.go b/internal/config/config_validation_internal_test.go
index c275e38..c269a38 100644
--- a/internal/config/config_validation_internal_test.go
+++ b/internal/config/config_validation_internal_test.go
@@ -771,6 +771,7 @@ func invalidSizeAndOriginCases() []abortCase {
 		"https://example.123",       // a host name whose last part is a number
 		"https://[0:0:0:0:0:0:0:1]", // an IPv6 address not in its shortest form
 		"file://example.com",        // a scheme other than http or https
+		"HTTPS://example.com",       // a scheme in upper case
 		"https://Example.com",       // a host name in upper case
 	}