diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7fbfd909..74cf263b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/).
 
 ### Fixed
 - Inline enums are now available during runtime as well
+- Inline enums can now be used as action parameter types as well. These enums will not have a runtime representation, but will only assert type safety!
 
 ## Version 0.14.0 - 2023-12-13
 ### Added
diff --git a/lib/components/enum.js b/lib/components/enum.js
index bcf08c15..afd27d46 100644
--- a/lib/components/enum.js
+++ b/lib/components/enum.js
@@ -29,17 +29,33 @@ function printEnum(buffer, name, kvs, options = {}) {
     buffer.add('// enum')
     buffer.add(`${opts.export ? 'export ' : ''}const ${name} = {`)
     buffer.indent()
-    const vals = new Set()
     for (const [k, v] of kvs) {
         buffer.add(`${k}: ${v},`)
-        vals.add(v?.val ?? v)  // in case of wrapped vals we need to unwrap here for the type
     }
     buffer.outdent()
     buffer.add('} as const;')
-    buffer.add(`${opts.export ? 'export ' : ''}type ${name} = ${[...vals].join(' | ')}`)
+    buffer.add(`${opts.export ? 'export ' : ''}type ${name} = ${stringifyEnumType(kvs)}`)
     buffer.add('')
 }
 
+/**
+ * Stringifies a list of enum key-value pairs into the righthand side of a TS type.
+ * @param {[string, string][]} kvs list of key-value pairs
+ * @returns {string} a stringified type
+ * @example
+ * ```js
+ * ['A', 'B', 'A'] // -> '"A" | "B"'
+ * ```
+ */
+const stringifyEnumType = kvs => [...uniqueValues(kvs)].join(' | ')
+
+/**
+ * Extracts all unique values from a list of enum key-value pairs.
+ * If the value is an object, then the `.val` property is used.
+ * @param {[string, any | {val: any}][]} kvs
+ */
+const uniqueValues = kvs => new Set(kvs.map(([,v]) => v?.val ?? v))  // in case of wrapped vals we need to unwrap here for the type
+
 // in case of strings, wrap in quotes and fallback to key to make sure values are attached for every key
 const enumVal = (key, value, enumType) => enumType === 'cds.String' ? JSON.stringify(`${value ?? key}`) : value
 
@@ -113,5 +129,6 @@ module.exports = {
     csnToEnumPairs,
     propertyToInlineEnumName,
     isInlineEnumType,
-    stringifyEnumImplementation
+    stringifyEnumImplementation,
+    stringifyEnumType
 }
\ No newline at end of file
diff --git a/lib/visitor.js b/lib/visitor.js
index 61fe2397..44a0af92 100644
--- a/lib/visitor.js
+++ b/lib/visitor.js
@@ -9,7 +9,7 @@ const { FlatInlineDeclarationResolver, StructuredInlineDeclarationResolver } = r
 const { Resolver } = require('./components/resolver')
 const { Logger } = require('./logging')
 const { docify } = require('./components/wrappers')
-const { csnToEnumPairs, propertyToInlineEnumName, isInlineEnumType } = require('./components/enum')
+const { csnToEnumPairs, propertyToInlineEnumName, isInlineEnumType, stringifyEnumType } = require('./components/enum')
 
  /** @typedef {import('./file').File} File */
  /** @typedef {{ entity: String }} Context */
@@ -313,11 +313,17 @@ class Visitor {
                 .filter(([, type]) => type?.type !== '$self' && !(type.items?.type === '$self'))
                 .map(([name, type]) => [
                     name,
-                    this.resolver.visitor.inlineDeclarationResolver.getPropertyDatatype(this.resolver.resolveAndRequire(type, file)),
+                    this.#stringifyFunctionParamType(type, file)
                 ])
             : []
     }
 
+    #stringifyFunctionParamType(type, file) {
+        return type.enum
+            ? stringifyEnumType(csnToEnumPairs(type))
+            : this.inlineDeclarationResolver.getPropertyDatatype(this.resolver.resolveAndRequire(type, file))
+    }
+
     #printFunction(name, func) {
         // FIXME: mostly duplicate of printAction -> reuse
         this.logger.debug(`Printing function ${name}:\n${JSON.stringify(func, null, 2)}`)
diff --git a/test/ast.js b/test/ast.js
index 2e75015e..69904e18 100644
--- a/test/ast.js
+++ b/test/ast.js
@@ -444,6 +444,7 @@ const check = {
     isUnionType: (node, of = []) => checkKeyword(node, 'uniontype') 
         && of.reduce((acc, predicate) => acc && node.subtypes.some(st => predicate(st)), true),
     isNullable: (node, of = []) => check.isUnionType(node, of.concat([check.isNull])),
+    isLiteral: (node, literal = undefined) => checkKeyword(node, 'literaltype') && (literal === undefined || node.literal === literal),
 }
 
 
diff --git a/test/unit/enum.test.js b/test/unit/enum.test.js
index 4e14e11b..f43b655b 100644
--- a/test/unit/enum.test.js
+++ b/test/unit/enum.test.js
@@ -3,12 +3,35 @@
 const fs = require('fs').promises
 const path = require('path')
 const cds2ts = require('../../lib/compile')
-const { ASTWrapper, check, JSASTWrapper } = require('../ast')
+const { ASTWrapper, check, JSASTWrapper, checkFunction } = require('../ast')
 const { locations } = require('../util')
 
 const dir = locations.testOutput('enums_test')
 
 // FIXME: missing: inline enums (entity Foo { bar: String enum { ... }})
+describe('Enum Action Parameters', () => {
+    let astw
+
+    beforeEach(async () => await fs.unlink(dir).catch(() => {}))
+    beforeAll(async () => {
+        const paths = await cds2ts
+            .compileFromFile(locations.unit.files('enums/actions.cds'), { outputDirectory: dir, inlineDeclarations: 'structured' })
+        astw = new ASTWrapper(path.join(paths[1], 'index.ts'))
+    })
+    
+    test('Coalescing Assignment Present', () => {
+        const actions = astw.getAspectProperty('_FoobarAspect', 'actions')
+        checkFunction(actions.type.members.find(fn => fn.name === 'f'), {
+            parameterCheck: ({members: [fst]}) => fst.name === 'p'
+                && check.isUnionType(fst.type, [
+                    t => check.isLiteral(t, 'A'),
+                    t => check.isLiteral(t, 'b'),
+                ])
+        })
+    }) 
+})
+
+
 describe('Nested Enums', () => {
     let astw
 
@@ -26,8 +49,6 @@ describe('Nested Enums', () => {
         const { left } = enm.expression
         // not checking the entire object chain here...
         expect(left.property.name).toBe('someEnumProperty')
-
-        console.log(42)
     }) 
 })
 
diff --git a/test/unit/files/enums/actions.cds b/test/unit/files/enums/actions.cds
new file mode 100644
index 00000000..2dc2ae9f
--- /dev/null
+++ b/test/unit/files/enums/actions.cds
@@ -0,0 +1,6 @@
+entity Foobar {} actions {
+  action f(p: String enum {
+    A;
+    B = 'b'
+  })
+};
\ No newline at end of file