diff --git a/index.ts b/index.ts
index ca9654e..f6fb5dd 100644
--- a/index.ts
+++ b/index.ts
@@ -1452,9 +1452,11 @@ export class RFC5424 extends RFC {
         return '[' + [
           sdId,
           ...Object.entries(sdParam)
-            .map(([name, value]) =>
-              `${name}="${RFC5424.escapeParamValue(value)}"`
-            ),
+            .reduce((array, [name, value]) => [
+              ...array,
+              ...(Array.isArray(value) ? value : [value])
+                .map((v) => `${name}="${RFC5424.escapeParamValue(v)}"`),
+            ], []),
         ].join(' ') + ']';
       }).join('');
     }
diff --git a/tests/syslog.test.js b/tests/syslog.test.js
index e86b71c..ee16f6f 100644
--- a/tests/syslog.test.js
+++ b/tests/syslog.test.js
@@ -456,7 +456,7 @@ describe('RFC5424 Class Tests', () => {
       structuredData: {
         "hi@32473": {
           foo: 1,
-          bar: 2
+          bar: [2, 3]
         },
         escape: {
           quoteCharacter: '"',
@@ -465,7 +465,7 @@ describe('RFC5424 Class Tests', () => {
         }
       }
     });
-    expect(result).toMatch(/^<190>1 \S+ \S+ - - - \[hi@32473 foo="1" bar="2"\]\[escape quoteCharacter="\\"" backslack="\\\\" closingBrace="\\]"\] BOMhello\n$/);
+    expect(result).toMatch(/^<190>1 \S+ \S+ - - - \[hi@32473 foo="1" bar="2" bar="3"\]\[escape quoteCharacter="\\"" backslack="\\\\" closingBrace="\\]"\] BOMhello\n$/);
   });
   test('RFC5424 BuildMessage with octet-counting', () => {
     const rfc5424 = new SyslogPro.RFC5424({