diff --git a/src/parser/parser.test.ts b/src/parser/parser.test.ts
index bba3e68..93e70c9 100644
--- a/src/parser/parser.test.ts
+++ b/src/parser/parser.test.ts
@@ -121,4 +121,41 @@ Cooldown: 5:30 70%..45%
       ]
     `);
   });
+
+  const parseInterval = (interval: string) =>
+    parse(`Name: My Workout\n${interval}`).intervals[0];
+
+  it("parses correct duration formats", () => {
+    expect(parseInterval("Interval: 0:10 50%").duration).toEqual(10);
+    expect(parseInterval("Interval: 00:10 50%").duration).toEqual(10);
+    expect(parseInterval("Interval: 0:00:10 50%").duration).toEqual(10);
+    expect(parseInterval("Interval: 0:02:05 50%").duration).toEqual(125);
+    expect(parseInterval("Interval: 1:00:00 50%").duration).toEqual(3600);
+    expect(parseInterval("Interval: 1:00:0 50%").duration).toEqual(3600);
+    expect(parseInterval("Interval: 1:0:0 50%").duration).toEqual(3600);
+    expect(parseInterval("Interval: 10:00:00 50%").duration).toEqual(36000);
+  });
+
+  it("throws error for incorrect duration formats", () => {
+    expect(() =>
+      parseInterval("Interval: 10 50%")
+    ).toThrowErrorMatchingInlineSnapshot(
+      `"Unrecognized interval parameter \\"10\\""`
+    );
+    expect(() =>
+      parseInterval("Interval: :10 50%")
+    ).toThrowErrorMatchingInlineSnapshot(
+      `"Unrecognized interval parameter \\":10\\""`
+    );
+    expect(() =>
+      parseInterval("Interval: 0:100 50%")
+    ).toThrowErrorMatchingInlineSnapshot(
+      `"Unrecognized interval parameter \\"0:100\\""`
+    );
+    expect(() =>
+      parseInterval("Interval: 00:00:00:10 50%")
+    ).toThrowErrorMatchingInlineSnapshot(
+      `"Unrecognized interval parameter \\"00:00:00:10\\""`
+    );
+  });
 });
diff --git a/src/parser/tokenizer.ts b/src/parser/tokenizer.ts
index d09828d..b87ec0e 100644
--- a/src/parser/tokenizer.ts
+++ b/src/parser/tokenizer.ts
@@ -50,7 +50,7 @@ const toSeconds = (str: string): number => {
 const toFraction = (percentage: number): number => percentage / 100;
 
 const tokenizeValueParam = (text: string): Token => {
-  if (/^[0-9:]+$/.test(text)) {
+  if (/^([0-9]{1,2}:)?[0-9]{1,2}:[0-9]{1,2}$/.test(text)) {
     return { type: "duration", value: toSeconds(text) };
   }
   if (/^[0-9]+rpm$/.test(text)) {
@@ -63,7 +63,7 @@ const tokenizeValueParam = (text: string): Token => {
   if (/^[0-9]+%$/.test(text)) {
     return { type: "intensity", value: toFraction(toInteger(text)) };
   }
-  throw new Error(`Unrecognized parameter "${text}"`);
+  throw new Error(`Unrecognized interval parameter "${text}"`);
 };
 
 const tokenizeParams = (type: LabelTokenValue, text: string): Token[] => {