diff --git a/.buildkite/pipeline.extra-steps.gradle b/.buildkite/pipeline.extra-steps.gradle
index 3ade4f9..9b54773 100644
--- a/.buildkite/pipeline.extra-steps.gradle
+++ b/.buildkite/pipeline.extra-steps.gradle
@@ -5,12 +5,13 @@ environment {
 blockStep 'Wait a minute!'
 
 commandStep {
+    def xVal = 1
     plugin 'foobar', [
         name: 'Baz',
         list: [
-            [
-                x: 1
-            ],
+            {
+                x = xVal
+            },
             [
                 x: 2
             ]
diff --git a/build.gradle b/build.gradle
index bb30c27..a7a1ad1 100644
--- a/build.gradle
+++ b/build.gradle
@@ -70,6 +70,12 @@ buildkite {
 
             plugin 'Widen/gradle#v1', {
                 tasks 'check'
+                systemProperties "com.widen.plugins.buildkite.foo": "bar"
+                foo = [
+                    {
+                        bar = 2
+                    }
+                ]
             }
         }
 
diff --git a/buildSrc/src/main/groovy/com/widen/plugins/buildkite/BuildkitePipeline.groovy b/buildSrc/src/main/groovy/com/widen/plugins/buildkite/BuildkitePipeline.groovy
index 79fe91b..73a28fd 100644
--- a/buildSrc/src/main/groovy/com/widen/plugins/buildkite/BuildkitePipeline.groovy
+++ b/buildSrc/src/main/groovy/com/widen/plugins/buildkite/BuildkitePipeline.groovy
@@ -1,6 +1,5 @@
 package com.widen.plugins.buildkite
 
-import groovy.json.JsonBuilder
 import groovy.json.JsonOutput
 import org.gradle.api.Project
 
@@ -212,11 +211,7 @@ class BuildkitePipeline implements ConfigurableEnvironment {
          * syntax for the plugin name.
          */
         void plugin(String name, Object config = null) {
-            if (config instanceof Closure) {
-                def builder = new JsonBuilder()
-                builder.call(config)
-                config = builder.content
-            }
+            config = PluginBuilder.expand(config)
 
             // If no version is given and a default version is defined, set it.
             if (!name.contains("#") && buildkite.pluginVersions.containsKey(name)) {
diff --git a/buildSrc/src/main/groovy/com/widen/plugins/buildkite/PluginBuilder.groovy b/buildSrc/src/main/groovy/com/widen/plugins/buildkite/PluginBuilder.groovy
new file mode 100644
index 0000000..93a5285
--- /dev/null
+++ b/buildSrc/src/main/groovy/com/widen/plugins/buildkite/PluginBuilder.groovy
@@ -0,0 +1,48 @@
+package com.widen.plugins.buildkite
+
+class PluginBuilder {
+    protected final Map<String, Object> model = [:]
+
+    static Object expand(Object value) {
+        if (value instanceof Closure) {
+            def builder = new PluginBuilder()
+            Closure cloned = (Closure) value.clone()
+            cloned.delegate = builder
+            cloned.resolveStrategy = Closure.DELEGATE_FIRST
+            cloned.call()
+            value = builder.model
+        }
+
+        if (value instanceof Map) {
+            return value.collectEntries {
+                [(it.key): expand(it.value)]
+            }
+        }
+
+        if (value instanceof Iterable) {
+            return value.collect {
+                expand(it)
+            }
+        }
+
+        return value
+    }
+
+    Object invokeMethod(String name, Object args) {
+        Collection expandedArgs = args.collect {
+            expand(it)
+        }
+
+        if (expandedArgs.isEmpty()) {
+            model[name] = null
+        } else if (expandedArgs.size() == 1) {
+            model[name] = expandedArgs[0]
+        } else {
+            model[name] = expandedArgs
+        }
+    }
+
+    void setProperty(String propertyName, Object newValue) {
+        model[propertyName] = expand(newValue)
+    }
+}
diff --git a/buildSrc/src/main/resources/idea.gdsl b/buildSrc/src/main/resources/idea.gdsl
new file mode 100644
index 0000000..49993a0
--- /dev/null
+++ b/buildSrc/src/main/resources/idea.gdsl
@@ -0,0 +1,5 @@
+def ctx = context(pathRegexp: /.*\/pipeline(\.[^.]+)?\.gradle/)
+
+contributor(ctx) {
+    delegatesTo(findClass('com.widen.plugins.buildkite.BuildkitePipeline'))
+}
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index e0b3fb8..8522e8f 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,6 @@
+#Wed Oct 21 16:26:08 CDT 2020
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.10.2-all.zip
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.10.2-bin.zip
-zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME