diff --git a/str.mjs b/str.mjs
index 4e61fb4..9e9b899 100644
--- a/str.mjs
+++ b/str.mjs
@@ -186,6 +186,8 @@ class Parser {
             }),
             contains: () => ({ command: 'contains', find: this.popToken() }),
             missing: () => ({ command: 'missing', find: this.popToken() }),
+            upper: () => ({ command: 'upper' }),
+            lower: () => ({ command: 'lower' }),
 
             help: () => ({ command: 'help' }),
             show: () => ({ command: 'show' }),
@@ -616,6 +618,8 @@ class VM {
                     this.resolveImmediate(cmd.offset) + (this.resolveImmediate(cmd.len) || subject.length))
                 .reverse()
                 .join(''),
+            upper: () => subject.toUpperCase(),
+            lower: () => subject.toLowerCase(),
             // reparse,
 
             help: () => {