diff --git a/data/rules/instantly.yml b/data/rules/instantly.yml
index 4e361ce..2331cb8 100644
--- a/data/rules/instantly.yml
+++ b/data/rules/instantly.yml
@@ -11,7 +11,7 @@ rules:
       (?:.|[\n\r]){0,16}?
       \b
       (
-        [A-Za-z0-9+/]{66}==
+        [A-Z0-9+/]{66}==
       )
     pattern_requirements:
       min_digits: 4