diff --git a/src/common/parsers/ISOFormatParser.ts b/src/common/parsers/ISOFormatParser.ts
index e1ef0dcd..fedb778d 100644
--- a/src/common/parsers/ISOFormatParser.ts
+++ b/src/common/parsers/ISOFormatParser.ts
@@ -16,7 +16,7 @@ const PATTERN = new RegExp(
     "(?:T" + //..
         "([0-9]{1,2}):([0-9]{1,2})" + // hh:mm
         "(?:" +
-            ":([0-9]{1,2})(?:\\.(\\d{1,4}))?" +
+            ":([0-9]{1,2})(?:\\.(\\d+))?" +
         ")?" + // :ss.s
         "(" +
             "Z|([+-]\\d{2}):?(\\d{2})?" +
@@ -57,7 +57,7 @@ export default class ISOFormatParser extends AbstractParserWithWordBoundaryCheck
             }
 
             if (match[MILLISECOND_NUMBER_GROUP] != null) {
-                components.assign("millisecond", parseInt(match[MILLISECOND_NUMBER_GROUP]));
+                components.assign("millisecond", parseInt(match[MILLISECOND_NUMBER_GROUP].padEnd(3, "0").slice(0, 3)));
             }
             if (match[TZD_GROUP] != null) {
                 // The Zulu time zone (Z) is equivalent to UTC
diff --git a/test/en/en_inter_std.test.ts b/test/en/en_inter_std.test.ts
index 7200487e..70b4eb9a 100644
--- a/test/en/en_inter_std.test.ts
+++ b/test/en/en_inter_std.test.ts
@@ -116,3 +116,33 @@ test("Test - Single Expression with local timezeon", function () {
         expect(result.start).toBeDate(new Date("2015-07-31T12:00:00"));
     });
 });
+
+test("Test - ISO 8601 with 6 fractional-second digits and a positive offset", function () {
+    testSingleCase(chrono, "2024-03-10T10:00:00.123456+05:30", new Date(2012, 7, 8), (result) => {
+        expect(result.text).toBe("2024-03-10T10:00:00.123456+05:30");
+        expect(result.start.get("second")).toBe(0);
+        expect(result.start.get("millisecond")).toBe(123);
+        expect(result.start.isCertain("timezoneOffset")).toBe(true);
+        expect(result.start).toBeDate(new Date("2024-03-10T04:30:00.123Z"));
+    });
+});
+
+test("Test - ISO 8601 with 5 fractional-second digits and a negative offset", function () {
+    testSingleCase(chrono, "2024-03-10T10:00:00.12345-05:00", new Date(2012, 7, 8), (result) => {
+        expect(result.text).toBe("2024-03-10T10:00:00.12345-05:00");
+        expect(result.start.get("second")).toBe(0);
+        expect(result.start.get("millisecond")).toBe(123);
+        expect(result.start.isCertain("timezoneOffset")).toBe(true);
+        expect(result.start).toBeDate(new Date("2024-03-10T15:00:00.123Z"));
+    });
+});
+
+test("Test - ISO 8601 with 9 fractional-second digits and Z", function () {
+    testSingleCase(chrono, "2024-03-10T10:00:00.123456789Z", new Date(2012, 7, 8), (result) => {
+        expect(result.text).toBe("2024-03-10T10:00:00.123456789Z");
+        expect(result.start.get("second")).toBe(0);
+        expect(result.start.get("millisecond")).toBe(123);
+        expect(result.start.isCertain("timezoneOffset")).toBe(true);
+        expect(result.start).toBeDate(new Date("2024-03-10T10:00:00.123Z"));
+    });
+});