diff --git a/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/system/EmbeddedServerPortFileWriter.java b/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/system/EmbeddedServerPortFileWriter.java
index 2bf26637e6..539cf1bc13 100644
--- a/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/system/EmbeddedServerPortFileWriter.java
+++ b/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/system/EmbeddedServerPortFileWriter.java
@@ -35,6 +35,8 @@ import org.springframework.util.StringUtils;
  *
  * @author David Liu
  * @author Phillip Webb
+ * @author Andy Wilkinson
+ *
  * @since 1.2.0
  */
 public class EmbeddedServerPortFileWriter implements
@@ -122,7 +124,8 @@ public class EmbeddedServerPortFileWriter implements
 
 	private boolean isUpperCase(String name) {
 		for (int i = 0; i < name.length(); i++) {
-			if (!Character.isUpperCase(name.charAt(i))) {
+			if (Character.isLetter(name.charAt(i))
+					&& !Character.isUpperCase(name.charAt(i))) {
 				return false;
 			}
 		}
diff --git a/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/system/EmbeddedServerPortFileWriterTests.java b/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/system/EmbeddedServerPortFileWriterTests.java
index 31f9455e9a..5393cf0c55 100644
--- a/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/system/EmbeddedServerPortFileWriterTests.java
+++ b/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/system/EmbeddedServerPortFileWriterTests.java
@@ -18,6 +18,8 @@ package org.springframework.boot.actuate.system;
 
 import java.io.File;
 import java.io.FileReader;
+import java.util.HashSet;
+import java.util.Set;
 
 import org.junit.After;
 import org.junit.Before;
@@ -31,6 +33,7 @@ import org.springframework.util.FileCopyUtils;
 import org.springframework.util.StringUtils;
 
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.hasItem;
 import static org.junit.Assert.assertThat;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.Mockito.mock;
@@ -40,6 +43,7 @@ import static org.mockito.Mockito.mock;
  *
  * @author David Liu
  * @author Phillip Webb
+ * @author Andy Wilkinson
  */
 public class EmbeddedServerPortFileWriterTests {
 
@@ -84,6 +88,7 @@ public class EmbeddedServerPortFileWriterTests {
 				+ StringUtils.getFilenameExtension(file.getName());
 		assertThat(FileCopyUtils.copyToString(new FileReader(new File(file
 				.getParentFile(), managementFile))), equalTo("9090"));
+		assertThat(collectFileNames(file.getParentFile()), hasItem(managementFile));
 	}
 
 	@Test
@@ -99,7 +104,7 @@ public class EmbeddedServerPortFileWriterTests {
 				+ StringUtils.getFilenameExtension(file.getName());
 		assertThat(FileCopyUtils.copyToString(new FileReader(new File(file
 				.getParentFile(), managementFile))), equalTo("9090"));
-
+		assertThat(collectFileNames(file.getParentFile()), hasItem(managementFile));
 	}
 
 	private EmbeddedServletContainerInitializedEvent mockEvent(String name, int port) {
@@ -112,4 +117,14 @@ public class EmbeddedServerPortFileWriterTests {
 		return event;
 	}
 
+	private Set<String> collectFileNames(File directory) {
+		Set<String> names = new HashSet<String>();
+		if (directory.isDirectory()) {
+			for (File file : directory.listFiles()) {
+				names.add(file.getName());
+			}
+		}
+		return names;
+	}
+
 }