diff --git a/.buildkite/pipeline.extra-steps.gradle b/.buildkite/pipeline.extra-steps.gradle
index bd92d91..3ade4f9 100644
--- a/.buildkite/pipeline.extra-steps.gradle
+++ b/.buildkite/pipeline.extra-steps.gradle
@@ -29,6 +29,12 @@ commandStep {
     // Common Buildkite plugins are also part of the DSL.
     dockerCompose {
         run 'unit'
+        // Passthrough variables
+        environment(
+            'FOO',
+            'BAR',
+            'BAZ',
+        )
     }
 }
 
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 5075d7b..79fe91b 100644
--- a/buildSrc/src/main/groovy/com/widen/plugins/buildkite/BuildkitePipeline.groovy
+++ b/buildSrc/src/main/groovy/com/widen/plugins/buildkite/BuildkitePipeline.groovy
@@ -259,12 +259,12 @@ class BuildkitePipeline implements ConfigurableEnvironment {
             }
 
             /**
-             * Set an environment variable to pass into the Docker container.
+             * Set one or more environment variables to pass into the Docker container.
              *
-             * @param name The variable name.
+             * @param name The variable names.
              */
-            void environment(String name) {
-                model.get('environment', []) << name
+            void environment(String... names) {
+                model.get('environment', []).addAll(names)
             }
 
             /**
@@ -383,10 +383,12 @@ class BuildkitePipeline implements ConfigurableEnvironment {
             }
 
             /**
-             * Set an environment variable to pass into the container.
+             * Set one or more environment variables to pass into the Docker container.
+             *
+             * @param name The variable names.
              */
-            void environment(String name) {
-                model.get('env', []) << name
+            void environment(String... names) {
+                model.get('env', []).addAll(names)
             }
 
             /**