diff --git a/src/parser/parser.test.ts b/src/parser/parser.test.ts
index 20ea7e3..c1a9894 100644
--- a/src/parser/parser.test.ts
+++ b/src/parser/parser.test.ts
@@ -653,4 +653,15 @@ Interval: 2:00 90%
 `),
     ).toThrowErrorMatchingInlineSnapshot(`"Comment offset is larger than interval length at line 5 char 5"`);
   });
+
+  it("throws error when negative comment offset is outside of interval", () => {
+    expect(() =>
+      parse(`
+Name: My Workout
+Interval: 2:00 90%
+  @ 0:00 Find your rythm.
+  @ -3:10 Try to settle in for the effort
+`),
+    ).toThrowErrorMatchingInlineSnapshot(`"Negative comment offset is larger than interval length at line 5 char 5"`);
+  });
 });
diff --git a/src/parser/validate.ts b/src/parser/validate.ts
index 94e8ddb..0830450 100644
--- a/src/parser/validate.ts
+++ b/src/parser/validate.ts
@@ -1,15 +1,14 @@
-import { Workout, Interval, Comment } from "../ast";
+import { Workout, Interval } from "../ast";
 import { ValidationError } from "./ValidationError";
 
-const isCommentWithinInterval = (comment: Comment, interval: Interval): boolean => {
-  return comment.offset.seconds < interval.duration.seconds;
-};
-
 const validateCommentOffsets = (interval: Interval) => {
   for (const comment of interval.comments) {
-    if (!isCommentWithinInterval(comment, interval)) {
+    if (comment.offset.seconds >= interval.duration.seconds) {
       throw new ValidationError(`Comment offset is larger than interval length`, comment.loc);
     }
+    if (comment.offset.seconds < 0) {
+      throw new ValidationError(`Negative comment offset is larger than interval length`, comment.loc);
+    }
   }
 };