diff --git a/src/DataParser.ts b/src/DataParser.ts
index 475bb82..4fd1d47 100644
--- a/src/DataParser.ts
+++ b/src/DataParser.ts
@@ -1,8 +1,8 @@
 import { InfoMetadata, NestedFieldMetadata } from "./MetadataParser";
-import { parseTypedValue, Value } from "./ValueParser";
+import { parseTypedValue, Value, ValueArray } from "./ValueParser";
 
-export function parseValue(token: string, infoMetadata: InfoMetadata): Value | Value[] {
-  let value: Value | Value[];
+export function parseValue(token: string, infoMetadata: InfoMetadata): Value | ValueArray {
+  let value: Value | ValueArray;
   const type = infoMetadata.number.type;
   switch (type) {
     case "NUMBER":
@@ -25,7 +25,7 @@ export function parseValue(token: string, infoMetadata: InfoMetadata): Value | V
   return value;
 }
 
-export function parseSingleValue(token: string, infoMetadata: InfoMetadata): Value | Value[] {
+export function parseSingleValue(token: string, infoMetadata: InfoMetadata): Value | ValueArray {
   let value: Value | Value[];
   if (infoMetadata.nested) {
     value = parseNestedValue(token, infoMetadata.nested);
@@ -35,21 +35,21 @@ export function parseSingleValue(token: string, infoMetadata: InfoMetadata): Val
   return value;
 }
 
-export function parseMultiValue(token: string, infoMetadata: InfoMetadata): Value[] {
+export function parseMultiValue(token: string, infoMetadata: InfoMetadata): ValueArray {
   const values: Value[] = [];
   if (token.length > 0) {
     for (const part of token.split(infoMetadata.number.separator as string)) {
-      values.push(parseSingleValue(part, infoMetadata) as Value);
+      values.push(parseSingleValue(part, infoMetadata));
     }
   }
   return values;
 }
 
-export function parseNestedValue(token: string, nestedInfoMetadata: NestedFieldMetadata): Value[] {
+export function parseNestedValue(token: string, nestedInfoMetadata: NestedFieldMetadata): ValueArray {
   const infoValues: Value[] = [];
   const parts = token.split(nestedInfoMetadata.separator);
   for (let i = 0; i < parts.length; ++i) {
-    infoValues.push(parseValue(parts[i], nestedInfoMetadata.items[i]) as Value);
+    infoValues.push(parseValue(parts[i], nestedInfoMetadata.items[i]));
   }
   return infoValues;
 }
diff --git a/src/SampleDataParser.ts b/src/SampleDataParser.ts
index 334e695..a9a1955 100644
--- a/src/SampleDataParser.ts
+++ b/src/SampleDataParser.ts
@@ -1,12 +1,12 @@
 import { FieldMetadata } from "./MetadataParser";
 import { parseValue } from "./DataParser";
-import { parseIntegerValue, Value } from "./ValueParser";
+import { parseIntegerValue, Value, ValueArray } from "./ValueParser";
 
 export interface RecordSample {
   [index: string]: RecordSampleType;
 }
 
-export type RecordSampleType = Genotype | Value | Value[];
+export type RecordSampleType = Genotype | Value | ValueArray;
 export type GenotypeAllele = number | null;
 export type GenotypeType = "het" | "hom_a" | "hom_r" | "miss" | "part";
 
@@ -36,7 +36,7 @@ export function parseRecordSample(
 }
 
 export function parseFormatValue(token: string, formatMetadata: FieldMetadata): RecordSampleType {
-  let value: Genotype | Value | Value[];
+  let value: Genotype | Value | ValueArray;
   if (formatMetadata.id === "GT") {
     value = parseGenotype(token);
   } else {
diff --git a/src/ValueParser.ts b/src/ValueParser.ts
index 18ce1fd..549b743 100644
--- a/src/ValueParser.ts
+++ b/src/ValueParser.ts
@@ -1,7 +1,8 @@
 import { MISSING } from "./Constants";
 import { ValueType } from "./MetadataParser";
 
-export type Value = ValueCharacter | ValueFlag | ValueFloat | ValueInteger | ValueObject | ValueString;
+export type Value = ValueCharacter | ValueFlag | ValueFloat | ValueInteger | ValueObject | ValueString | ValueArray;
+export type ValueArray = Array<Value | Array<Value>>;
 export type ValueCharacter = string | null;
 export type ValueFlag = boolean | null;
 export type ValueFloat = number | null;
diff --git a/src/VcfParser.ts b/src/VcfParser.ts
index ab6682f..b83ea2f 100644
--- a/src/VcfParser.ts
+++ b/src/VcfParser.ts
@@ -5,6 +5,7 @@ import {
   parseStringArrayNonNullValues,
   parseStringValueNonNull,
   Value,
+  ValueArray,
 } from "./ValueParser";
 import { MISSING } from "./Constants";
 import { FieldMetadata, parseFormatMetadata, parseInfoMetadata } from "./MetadataParser";
@@ -22,7 +23,7 @@ export interface FieldMetadataContainer {
 }
 
 export interface InfoContainer {
-  [index: string]: Value | Value[];
+  [index: string]: Value | ValueArray;
 }
 
 export function parseVcf(vcf: string): Container {
diff --git a/src/VcfWriter.ts b/src/VcfWriter.ts
index 339901a..be7d6db 100644
--- a/src/VcfWriter.ts
+++ b/src/VcfWriter.ts
@@ -2,7 +2,7 @@ import { Container, FormatMetadataContainer, Genotype, Metadata, Record, RecordS
 import { MISSING } from "./Constants";
 import { FieldMetadataContainer, InfoContainer } from "./VcfParser";
 import { FieldMetadata, NestedFieldMetadata } from "./MetadataParser";
-import { Value } from "./ValueParser";
+import { Value, ValueArray } from "./ValueParser";
 import { RecordSampleType } from "./SampleDataParser";
 
 export type Filter = {
@@ -122,14 +122,14 @@ function writeInfo(infoFields: FieldMetadataContainer, infoValues: InfoContainer
   return vcf.join(";");
 }
 
-function writeInfoField(infoField: FieldMetadata, infoValue: Value | Value[]): string {
+function writeInfoField(infoField: FieldMetadata, infoValue: Value | ValueArray): string {
   let vcf;
   if (infoField.number.count === 0) {
     vcf = infoField.id;
   } else if (infoField.number.count === 1) {
-    vcf = infoField.id + "=" + writeFieldValueSingle(infoField, infoValue as Value);
+    vcf = infoField.id + "=" + writeFieldValueSingle(infoField, infoValue);
   } else {
-    vcf = infoField.id + "=" + writeFieldValueMultiple(infoField, infoValue as Value[], ",");
+    vcf = infoField.id + "=" + writeFieldValueMultiple(infoField, infoValue as ValueArray, ",");
   }
   return vcf;
 }
@@ -137,19 +137,19 @@ function writeInfoField(infoField: FieldMetadata, infoValue: Value | Value[]): s
 function writeFieldValueSingle(field: FieldMetadata, value: Value, missingValue = MISSING): string {
   let vcf;
   if (field.nested) {
-    vcf = writeFieldValueNested(field.nested, value as unknown as Value[]);
+    vcf = writeFieldValueNested(field.nested, value as ValueArray);
   } else {
     vcf = writeFieldValue(field, value, missingValue);
   }
   return vcf;
 }
 
-function writeFieldValueMultiple(field: FieldMetadata, values: Value[], separator: string): string {
+function writeFieldValueMultiple(field: FieldMetadata, values: ValueArray, separator: string): string {
   const vcf = [];
 
   for (const infoValue of values) {
     if (field.nested) {
-      vcf.push(writeFieldValueNested(field.nested, infoValue as unknown as Value[]));
+      vcf.push(writeFieldValueNested(field.nested, infoValue as ValueArray));
     } else {
       vcf.push(writeFieldValue(field, infoValue, ""));
     }
@@ -158,13 +158,13 @@ function writeFieldValueMultiple(field: FieldMetadata, values: Value[], separato
   return vcf.join(separator);
 }
 
-function writeFieldValueNested(nestedField: NestedFieldMetadata, nestedValues: Value[]): string {
+function writeFieldValueNested(nestedField: NestedFieldMetadata, nestedValues: ValueArray): string {
   const vcf = [];
   for (const [index, infoField] of nestedField.items.entries()) {
     if (infoField.number.count === 1) {
       vcf.push(writeFieldValueSingle(infoField, nestedValues[index], ""));
     } else {
-      vcf.push(writeFieldValueMultiple(infoField, nestedValues[index] as unknown as Value[], "&"));
+      vcf.push(writeFieldValueMultiple(infoField, nestedValues[index] as ValueArray, "&"));
     }
   }
   return vcf.join(nestedField.separator);
@@ -224,7 +224,7 @@ function writeSampleValue(formatField: FieldMetadata, value: RecordSampleType):
     } else if (formatField.number.count === 1) {
       vcf = writeFieldValueSingle(formatField, value as Value);
     } else {
-      vcf = writeFieldValueMultiple(formatField, value as Value[], ",");
+      vcf = writeFieldValueMultiple(formatField, value as ValueArray, ",");
     }
   }
   return vcf;
diff --git a/src/__tests__/VcfParser.test.ts b/src/__tests__/VcfParser.test.ts
index 1cc69ae..5d4af5e 100644
--- a/src/__tests__/VcfParser.test.ts
+++ b/src/__tests__/VcfParser.test.ts
@@ -1,6 +1,6 @@
 import { parseVcf } from "../VcfParser";
 import { Container } from "../Vcf";
-import { Value } from "../ValueParser";
+import { ValueArray } from "../ValueParser";
 
 // trailing info semicolon placed on purpose
 const vcf = `
@@ -197,7 +197,7 @@ test("parse vcf - escaped nested info values", () => {
             ["x0", "y0", "z0"],
             ["x1", "y1a,y1b", "z1"],
             ["x2", "y2", "z2"],
-          ] as unknown as Value,
+          ] as ValueArray,
         },
         s: [],
       },