diff --git a/spring-cloud-sleuth-stream/src/main/java/org/springframework/cloud/sleuth/stream/StreamEnvironmentPostProcessor.java b/spring-cloud-sleuth-stream/src/main/java/org/springframework/cloud/sleuth/stream/StreamEnvironmentPostProcessor.java
index 63c01e0b9..afa173813 100644
--- a/spring-cloud-sleuth-stream/src/main/java/org/springframework/cloud/sleuth/stream/StreamEnvironmentPostProcessor.java
+++ b/spring-cloud-sleuth-stream/src/main/java/org/springframework/cloud/sleuth/stream/StreamEnvironmentPostProcessor.java
@@ -84,7 +84,11 @@ public class StreamEnvironmentPostProcessor implements EnvironmentPostProcessor
 	private int findStartIndex(ConfigurableEnvironment environment, String binder) {
 		String prefix = "spring.cloud.stream." + binder + ".binder.headers";
 		int i = 0;
-		while (environment.getProperty(prefix + "[" + i + "]")!=null) {
+		String oldHeaders = environment.getProperty(prefix);
+		if (oldHeaders != null) {
+			i = oldHeaders.split(",").length;
+		}
+		while (environment.getProperty(prefix + "[" + i + "]") != null) {
 			i++;
 		}
 		return i;
diff --git a/spring-cloud-sleuth-stream/src/test/java/org/springframework/cloud/sleuth/stream/StreamEnvironmentPostProcessorTests.java b/spring-cloud-sleuth-stream/src/test/java/org/springframework/cloud/sleuth/stream/StreamEnvironmentPostProcessorTests.java
index ac8ba97f9..fb2088beb 100644
--- a/spring-cloud-sleuth-stream/src/test/java/org/springframework/cloud/sleuth/stream/StreamEnvironmentPostProcessorTests.java
+++ b/spring-cloud-sleuth-stream/src/test/java/org/springframework/cloud/sleuth/stream/StreamEnvironmentPostProcessorTests.java
@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.sleuth.stream;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 import java.util.Collection;
 import java.util.Map;
 import java.util.stream.Collectors;
@@ -27,8 +29,6 @@ import org.springframework.cloud.sleuth.instrument.messaging.TraceMessageHeaders
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.StandardEnvironment;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
 /**
  * @author Dave Syer
  *
@@ -57,6 +57,16 @@ public class StreamEnvironmentPostProcessorTests {
 						.isEqualTo(TraceMessageHeaders.SPAN_ID_NAME);
 	}
 
+	@Test
+	public void should_append_tracing_headers_to_existing_ones_in_single_line() {
+		EnvironmentTestUtils.addEnvironment(this.environment,
+				"spring.cloud.stream.test.binder.headers=foo,bar");
+		postProcess();
+		assertThat(this.environment
+				.getProperty("spring.cloud.stream.test.binder.headers[2]"))
+						.isEqualTo(TraceMessageHeaders.SPAN_ID_NAME);
+	}
+
 	@Test
 	public void should_not_append_tracing_headers_if_they_are_already_appended() {
 		postProcess();