diff --git a/language/tokens.ts b/language/tokens.ts
index aeac06fd..fa75bda5 100644
--- a/language/tokens.ts
+++ b/language/tokens.ts
@@ -35,7 +35,7 @@ const commonMatchers: Matcher[] = [
       { type: `divide` },
       {
         type: `word`,
-        match: (word) => [`TITLE`, `EJECT`, `SPACE`, `COPY`, `INCLUDE`, `SET`, `RESTORE`, `OVERLOAD`, `DEFINE`, `UNDEFINED`, `IF`, `ELSE`, `ELSEIF`, `ENDIF`, `EOF`, `CHARCOUNT`].includes(word.toUpperCase())
+        match: (word) => [`TITLE`, `EJECT`, `SPACE`, `COPY`, `INCLUDE`, `SET`, `RESTORE`, `OVERLOAD`, `DEFINE`, `UNDEFINE`, `IF`, `ELSE`, `ELSEIF`, `ENDIF`, `EOF`, `CHARCOUNT`].includes(word.toUpperCase())
       },
     ],
     becomes: {
diff --git a/tests/suite/linter.test.ts b/tests/suite/linter.test.ts
index ba2d475f..6aced4aa 100644
--- a/tests/suite/linter.test.ts
+++ b/tests/suite/linter.test.ts
@@ -3281,4 +3281,25 @@ test(`snd-msg casing #309`, async () => {
   }, cache);
 
   expect(errors.length).toBe(0);
-});
\ No newline at end of file
+});
+
+test(`define and undefine directives #310`, async () => {
+  const lines = [
+    `**free`,
+    `/define #stuff`,
+    `// do exciting things here`,
+    `/undefine #stuff`,
+    `dcl-ds gPSDS psds qualified;`,
+    `  pgmName *proc;`,
+    `end-ds;`,
+    `*inlr = *on;`,
+    `return;`,
+  ].join(`\n`);
+
+  const cache = await parser.getDocs(uri, lines, { ignoreCache: true, withIncludes: true });
+  const { indentErrors } = Linter.getErrors({ uri, content: lines }, {
+    indent: 2
+  }, cache);
+
+  expect(indentErrors.length).toBe(0);
+});