diff --git a/src/index.ts b/src/index.ts
index 9736cab..fe6a024 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -20,7 +20,7 @@ export enum Types {
 
 Object.freeze(Types);
 
-export type Tags = { [key: string]: string } | string[];
+export type Tags = { [key: string]: string | null } | string[];
 
 export interface Options {
     host?: string | URL;
@@ -132,7 +132,7 @@ class Client {
                 this.tags = tags.join(',');
             } else {
                 this.tags = Object.keys(tags)
-                    .map((tag) => `${tag}:${tags[tag]}`)
+                    .map((tag) => (tags[tag] ? `${tag}:${tags[tag]}` : tag))
                     .join(',');
             }
         }
diff --git a/test/index.spec.ts b/test/index.spec.ts
index 59ef9d9..7509def 100644
--- a/test/index.spec.ts
+++ b/test/index.spec.ts
@@ -114,11 +114,14 @@ test('counter with sampling', (t) => {
 test('counter with tags', (t) => {
     const host = new URL(`udp://127.0.0.1:${t.context.address.port}`);
     const namespace = 'ns1';
-    const tags = { tag1: 'value1', tag2: 'value2' };
+    const tags = { tag1: 'value1', tag2: null, tag3: 'value3' };
     const client = new Client({ host, namespace, tags });
     return new Promise<number>((resolve) => {
         t.context.server.on('metric', (metric) => {
-            t.is(`${namespace}.some.metric:1|c|@10|#tag1:value1,tag2:value2`, metric.toString());
+            t.is(
+                `${namespace}.some.metric:1|c|@10|#tag1:value1,tag2,tag3:value3`,
+                metric.toString()
+            );
             return resolve(0);
         });
         client.counter('some.metric', 1, 10);
@@ -154,11 +157,14 @@ test('timing with sampling', (t) => {
 test('timing with tags', (t) => {
     const host = new URL(`udp://127.0.0.1:${t.context.address.port}`);
     const namespace = 'ns1';
-    const tags = { tag1: 'value1', tag2: 'value2' };
+    const tags = { tag1: 'value1', tag2: null, tag3: 'value3' };
     const client = new Client({ host, namespace, tags });
     return new Promise<number>((resolve) => {
         t.context.server.on('metric', (metric) => {
-            t.is(`${namespace}.some.metric:1|ms|@10|#tag1:value1,tag2:value2`, metric.toString());
+            t.is(
+                `${namespace}.some.metric:1|ms|@10|#tag1:value1,tag2,tag3:value3`,
+                metric.toString()
+            );
             return resolve(0);
         });
         client.timing('some.metric', 1, 10);
@@ -194,11 +200,14 @@ test('gauge should ignore sampling', (t) => {
 test('gauge with tags', (t) => {
     const host = new URL(`udp://127.0.0.1:${t.context.address.port}`);
     const namespace = 'ns1';
-    const tags = { tag1: 'value1', tag2: 'value2' };
+    const tags = { tag1: 'value1', tag2: null, tag3: 'value3' };
     const client = new Client({ host, namespace, tags });
     return new Promise<number>((resolve) => {
         t.context.server.on('metric', (metric) => {
-            t.is(`${namespace}.some.metric:1|g|#tag1:value1,tag2:value2`, metric.toString());
+            t.is(
+                `${namespace}.some.metric:1|g|#tag1:value1,tag2,tag3:value3`,
+                metric.toString()
+            );
             return resolve(0);
         });
         client.gauge('some.metric', 1);
@@ -234,11 +243,14 @@ test('set should ignore sampling', (t) => {
 test('set with tags', (t) => {
     const host = new URL(`udp://127.0.0.1:${t.context.address.port}`);
     const namespace = 'ns1';
-    const tags = { tag1: 'value1', tag2: 'value2' };
+    const tags = { tag1: 'value1', tag2: null, tag3: 'value3' };
     const client = new Client({ host, namespace, tags });
     return new Promise<number>((resolve) => {
         t.context.server.on('metric', (metric) => {
-            t.is(`${namespace}.some.metric:1|s|#tag1:value1,tag2:value2`, metric.toString());
+            t.is(
+                `${namespace}.some.metric:1|s|#tag1:value1,tag2,tag3:value3`,
+                metric.toString()
+            );
             return resolve(0);
         });
         client.set('some.metric', 1);