diff --git a/src/main/java/org/jenkinsci/plugins/credentialsbinding/impl/SSHUserPrivateKeyBinding.java b/src/main/java/org/jenkinsci/plugins/credentialsbinding/impl/SSHUserPrivateKeyBinding.java
index 1bd0ae05..d59786ba 100644
--- a/src/main/java/org/jenkinsci/plugins/credentialsbinding/impl/SSHUserPrivateKeyBinding.java
+++ b/src/main/java/org/jenkinsci/plugins/credentialsbinding/impl/SSHUserPrivateKeyBinding.java
@@ -27,6 +27,7 @@
 import hudson.Extension;
 import hudson.FilePath;
 import hudson.Launcher;
+import hudson.Util;
 import hudson.model.Run;
 import hudson.model.TaskListener;
 import hudson.util.Secret;
@@ -53,8 +54,8 @@ public class SSHUserPrivateKeyBinding extends MultiBinding<SSHUserPrivateKey> {
     }
 
     @DataBoundSetter
-    public void setUsernameVariable(@Nonnull final String usernameVariable) {
-        this.usernameVariable = usernameVariable;
+    public void setUsernameVariable(@CheckForNull String usernameVariable) {
+        this.usernameVariable = Util.fixEmptyAndTrim(usernameVariable);
     }
 
     @CheckForNull
@@ -63,8 +64,8 @@ public String getUsernameVariable() {
     }
 
     @DataBoundSetter
-    public void setPassphraseVariable(@Nonnull final String passphraseVariable) {
-        this.passphraseVariable = passphraseVariable;
+    public void setPassphraseVariable(@CheckForNull String passphraseVariable) {
+        this.passphraseVariable = Util.fixEmptyAndTrim(passphraseVariable);
     }
 
     @CheckForNull
diff --git a/src/test/java/org/jenkinsci/plugins/credentialsbinding/impl/CertificateMultiBindingTest.java b/src/test/java/org/jenkinsci/plugins/credentialsbinding/impl/CertificateMultiBindingTest.java
index bf7225eb..f1f240b8 100644
--- a/src/test/java/org/jenkinsci/plugins/credentialsbinding/impl/CertificateMultiBindingTest.java
+++ b/src/test/java/org/jenkinsci/plugins/credentialsbinding/impl/CertificateMultiBindingTest.java
@@ -93,6 +93,8 @@ public void setUp() throws IOException {
 		}
 	}
 
+    // TODO configRoundtrip to test form, null hygiene on @DataBoundSetter
+
 	@Test
 	public void basics() throws Exception {
 		String alias = "androiddebugkey";
diff --git a/src/test/java/org/jenkinsci/plugins/credentialsbinding/impl/SSHUserPrivateKeyTest.java b/src/test/java/org/jenkinsci/plugins/credentialsbinding/impl/SSHUserPrivateKeyBindingTest.java
similarity index 87%
rename from src/test/java/org/jenkinsci/plugins/credentialsbinding/impl/SSHUserPrivateKeyTest.java
rename to src/test/java/org/jenkinsci/plugins/credentialsbinding/impl/SSHUserPrivateKeyBindingTest.java
index 27c43451..d2e606b3 100644
--- a/src/test/java/org/jenkinsci/plugins/credentialsbinding/impl/SSHUserPrivateKeyTest.java
+++ b/src/test/java/org/jenkinsci/plugins/credentialsbinding/impl/SSHUserPrivateKeyBindingTest.java
@@ -34,6 +34,7 @@
 import hudson.util.Secret;
 import org.jenkinsci.plugins.credentialsbinding.MultiBinding;
 import org.jenkinsci.plugins.workflow.cps.CpsFlowDefinition;
+import org.jenkinsci.plugins.workflow.cps.SnippetizerTester;
 import org.jenkinsci.plugins.workflow.job.WorkflowJob;
 import org.jenkinsci.plugins.workflow.job.WorkflowRun;
 import org.jenkinsci.plugins.workflow.steps.StepConfigTester;
@@ -51,7 +52,7 @@
 import org.junit.ClassRule;
 import org.jvnet.hudson.test.BuildWatcher;
 
-public class SSHUserPrivateKeyTest {
+public class SSHUserPrivateKeyBindingTest {
 
     @Rule public RestartableJenkinsRule story = new RestartableJenkinsRule();
     @ClassRule public static BuildWatcher bw = new BuildWatcher();
@@ -119,21 +120,22 @@ public CredentialsScope getScope() {
     }
 
     @Test public void configRoundTrip() throws Exception {
-        story.addStep(new Statement() {
-            @Override public void evaluate() throws Throwable {
-                SSHUserPrivateKey c = new DummyPrivateKey("creds", "bob", "secret", "the-key");
-                CredentialsProvider.lookupStores(story.j.jenkins).iterator().next().addCredentials(Domain.global(), c);
-                SSHUserPrivateKeyBinding binding = new SSHUserPrivateKeyBinding("keyFile", "creds");
-                binding.setPassphraseVariable("passphrase");
-                binding.setUsernameVariable("user");
-                BindingStep s = new StepConfigTester(story.j).configRoundTrip(new BindingStep(
-                        Collections.<MultiBinding>singletonList(binding)));
-                story.j.assertEqualDataBoundBeans(s.getBindings(), Collections.singletonList(binding));
-            }
+        story.then(r -> {
+            SnippetizerTester st = new SnippetizerTester(r);
+            SSHUserPrivateKey c = new DummyPrivateKey("creds", "bob", "secret", "the-key");
+            CredentialsProvider.lookupStores(story.j.jenkins).iterator().next().addCredentials(Domain.global(), c);
+            SSHUserPrivateKeyBinding binding = new SSHUserPrivateKeyBinding("keyFile", "creds");
+            BindingStep s = new StepConfigTester(story.j).configRoundTrip(new BindingStep(Collections.<MultiBinding>singletonList(binding)));
+            st.assertRoundTrip(s, "withCredentials([sshUserPrivateKey(credentialsId: 'creds', keyFileVariable: 'keyFile')]) {\n    // some block\n}");
+            r.assertEqualDataBoundBeans(s.getBindings(), Collections.singletonList(binding));
+            binding.setPassphraseVariable("passphrase");
+            binding.setUsernameVariable("user");
+            s = new StepConfigTester(story.j).configRoundTrip(new BindingStep(Collections.<MultiBinding>singletonList(binding)));
+            st.assertRoundTrip(s, "withCredentials([sshUserPrivateKey(credentialsId: 'creds', keyFileVariable: 'keyFile', passphraseVariable: 'passphrase', usernameVariable: 'user')]) {\n    // some block\n}");
+            r.assertEqualDataBoundBeans(s.getBindings(), Collections.singletonList(binding));
         });
     }
 
-
     @Test public void basics() throws Exception {
         final String credentialsId = "creds";
         final String username = "bob";