diff --git a/__tests__/unit/input-parsing.test.ts b/__tests__/unit/input-parsing.test.ts
index 31c06919..8ed36933 100644
--- a/__tests__/unit/input-parsing.test.ts
+++ b/__tests__/unit/input-parsing.test.ts
@@ -7,4 +7,8 @@ test('get input parameters', () => {
   expect(inputParameters.packages).toHaveLength(2)
   expect(inputParameters.packages).toContain('foo:1.2.3-quux')
   expect(inputParameters.packages).toContain('bar:4.5.6-xyzzy')
+  expect(inputParameters.customFields).toEqual({
+    key1: 'value',
+    key2: 'value:with:colons'
+  })
 })
diff --git a/src/input-parameters.ts b/src/input-parameters.ts
index 0566e9be..4902028f 100644
--- a/src/input-parameters.ts
+++ b/src/input-parameters.ts
@@ -35,7 +35,9 @@ export interface InputParameters {
 const createCustomFields = (inputParameters: string[]): Record<string, string> => {
   return inputParameters.reduce(
     (acc, field) => {
-      const [key, value] = field.split(':').map(part => part.trim())
+      const colonIndex = field.indexOf(':')
+      const key = field.slice(0, colonIndex).trim()
+      const value = field.slice(colonIndex + 1).trim()
       if (key && value) {
         acc[key] = value
       }
diff --git a/src/test-setup.ts b/src/test-setup.ts
index 1b947564..b6bacea0 100644
--- a/src/test-setup.ts
+++ b/src/test-setup.ts
@@ -9,6 +9,7 @@ process.env = Object.assign(process.env, {
   INPUT_DEBUG: false,
   INPUT_DEFAULT_PACKAGE_VERSION: false,
   INPUT_IGNORE_EXISTING: false,
+  INPUT_CUSTOM_FIELDS: 'key1:value \n key2:value:with:colons',
   INPUT_PACKAGES: ' foo:1.2.3-quux \n bar:4.5.6-xyzzy \n ',
   INPUT_PROJECT: 'Projects-7341',
   INPUT_SERVER: process.env['OCTOPUS_URL'],