diff --git a/lib/spec/swagger/utils.js b/lib/spec/swagger/utils.js
index 808c7c1d..1b0a55c0 100644
--- a/lib/spec/swagger/utils.js
+++ b/lib/spec/swagger/utils.js
@@ -155,6 +155,25 @@ function plainJsonObjectToSwagger2 (container, jsonSchema, externalSchemas, secu
     })
 }
 
+/*
+* Map  unsupported JSON schema definitions to Swagger definitions
+*/
+function replaceUnsupported (jsonSchema) {
+  if (typeof jsonSchema === 'object' && jsonSchema !== null) {
+    // Handle patternProperties, that is not part of OpenAPI definitions
+    if (jsonSchema.patternProperties) {
+      jsonSchema.additionalProperties = { type: 'string' }
+      delete jsonSchema.patternProperties
+    }
+
+    Object.keys(jsonSchema).forEach(function (key) {
+      jsonSchema[key] = replaceUnsupported(jsonSchema[key])
+    })
+  }
+
+  return jsonSchema
+}
+
 function isConsumesFormOnly (schema) {
   const consumes = schema.consumes
   return (
@@ -168,6 +187,8 @@ function isConsumesFormOnly (schema) {
 function resolveBodyParams (parameters, schema, ref) {
   const resolved = ref.resolve(schema)
 
+  replaceUnsupported(resolved)
+
   parameters.push({
     name: 'body',
     in: 'body',
@@ -224,6 +245,7 @@ function resolveResponse (fastifyResponseJson, ref) {
     // add schema when type is not 'null'
     if (rawJsonSchema.type !== 'null') {
       const schema = { ...resolved }
+      replaceUnsupported(schema)
       delete schema[xResponseDescription]
       response.schema = schema
     }
diff --git a/test/spec/swagger/schema.js b/test/spec/swagger/schema.js
index bb9f5486..d4a9fae1 100644
--- a/test/spec/swagger/schema.js
+++ b/test/spec/swagger/schema.js
@@ -415,3 +415,69 @@ test('fluent-json-schema', async t => {
   const definedPath = api.paths['/'].get
   t.same(definedPath.responses['200'].description, 'Default Response')
 })
+
+test('support "patternProperties" in json schema', async t => {
+  const opt = {
+    schema: {
+      body: {
+        type: 'object',
+        patternProperties: {
+          '^[a-z]{2,3}-[a-zA-Z]{2}$': {
+            type: 'string'
+          }
+        }
+      },
+      response: {
+        200: {
+          description: 'Expected Response',
+          type: 'object',
+          properties: {
+            foo: {
+              type: 'object',
+              patternProperties: {
+                '^[a-z]{2,3}-[a-zA-Z]{2}$': {
+                  type: 'string'
+                }
+              },
+              additionalProperties: false
+            }
+          }
+        }
+      }
+    }
+  }
+
+  const fastify = Fastify()
+  fastify.register(fastifySwagger, {
+    swagger: true,
+    routePrefix: '/docs',
+    exposeRoute: true
+  })
+  fastify.get('/', opt, () => {})
+
+  await fastify.ready()
+
+  const swaggerObject = fastify.swagger()
+  const api = await Swagger.validate(swaggerObject)
+
+  const definedPath = api.paths['/'].get
+
+  t.same(definedPath.parameters[0].schema, {
+    type: 'object',
+    additionalProperties: { type: 'string' }
+  })
+
+  t.same(definedPath.responses[200], {
+    description: 'Expected Response',
+    schema: {
+      description: 'Expected Response',
+      type: 'object',
+      properties: {
+        foo: {
+          type: 'object',
+          additionalProperties: { type: 'string' }
+        }
+      }
+    }
+  })
+})