diff --git a/spring-cloud-cli/src/main/java/org/springframework/cloud/cli/command/encrypt/BaseEncryptOptionHandler.java b/spring-cloud-cli/src/main/java/org/springframework/cloud/cli/command/encrypt/BaseEncryptOptionHandler.java
index 9cb2822..39c1961 100644
--- a/spring-cloud-cli/src/main/java/org/springframework/cloud/cli/command/encrypt/BaseEncryptOptionHandler.java
+++ b/spring-cloud-cli/src/main/java/org/springframework/cloud/cli/command/encrypt/BaseEncryptOptionHandler.java
@@ -66,6 +66,9 @@ class BaseEncryptOptionHandler extends OptionHandler {
 
 	protected TextEncryptor createEncryptor(OptionSet options) {
 		String value = keyOption.value(options);
+		if (value==null) {
+			throw new MissingKeyException();
+		}
 		if (options.has(passwordOption)) { // it's a keystore
 			String password = options.valueOf(passwordOption);
 			String alias = options.valueOf(aliasOption);
diff --git a/spring-cloud-cli/src/main/java/org/springframework/cloud/cli/command/encrypt/EncryptCommand.java b/spring-cloud-cli/src/main/java/org/springframework/cloud/cli/command/encrypt/EncryptCommand.java
index ab5e423..5734b34 100644
--- a/spring-cloud-cli/src/main/java/org/springframework/cloud/cli/command/encrypt/EncryptCommand.java
+++ b/spring-cloud-cli/src/main/java/org/springframework/cloud/cli/command/encrypt/EncryptCommand.java
@@ -31,7 +31,8 @@ import org.springframework.util.StringUtils;
 public class EncryptCommand extends OptionParsingCommand {
 
 	public EncryptCommand() {
-		super("encrypt", "Encrypt a string so, for isntance, it can be added to source control",
+		super("encrypt",
+				"Encrypt a string so, for isntance, it can be added to source control",
 				new EncryptOptionHandler());
 	}
 
diff --git a/spring-cloud-cli/src/main/java/org/springframework/cloud/cli/command/encrypt/MissingKeyException.java b/spring-cloud-cli/src/main/java/org/springframework/cloud/cli/command/encrypt/MissingKeyException.java
new file mode 100644
index 0000000..da6d161
--- /dev/null
+++ b/spring-cloud-cli/src/main/java/org/springframework/cloud/cli/command/encrypt/MissingKeyException.java
@@ -0,0 +1,26 @@
+/*
+ * Copyright 2012-2014 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.cloud.cli.command.encrypt;
+
+import org.springframework.boot.cli.command.CommandException;
+
+@SuppressWarnings("serial")
+public class MissingKeyException extends CommandException {
+
+	public MissingKeyException() {
+		super("Error: missing key (please use --key)");
+	}
+}
diff --git a/spring-cloud-cli/src/test/java/org/springframework/cloud/cli/command/encrypt/EncryptCommandTests.java b/spring-cloud-cli/src/test/java/org/springframework/cloud/cli/command/encrypt/EncryptCommandTests.java
index 84fca2a..13aaf2b 100644
--- a/spring-cloud-cli/src/test/java/org/springframework/cloud/cli/command/encrypt/EncryptCommandTests.java
+++ b/spring-cloud-cli/src/test/java/org/springframework/cloud/cli/command/encrypt/EncryptCommandTests.java
@@ -34,6 +34,11 @@ public class EncryptCommandTests {
 		assertEquals(ExitStatus.OK, command.run("-k", "deadbeef", "foo"));
 	}
 
+	@Test(expected=MissingKeyException.class)
+	public void errorOnNoKey() throws Exception {
+		assertEquals(ExitStatus.ERROR, command.run("foo"));
+	}
+
 	@Test(expected=IllegalStateException.class)
 	public void failsWithBadFile() throws Exception {
 		assertEquals(ExitStatus.OK, command.run("-k", "@nosuchfile", "foo"));