diff --git a/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/TraceFilter.java b/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/TraceFilter.java
index 0e9889403..4773fab11 100644
--- a/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/TraceFilter.java
+++ b/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/TraceFilter.java
@@ -364,6 +364,7 @@ public class TraceFilter extends GenericFilterBean {
 
 		final Span span;
 		final Tracer.SpanInScope scope;
+
 		SpanAndScope(Span span, Tracer.SpanInScope scope) {
 			this.span = span;
 			this.scope = scope;
diff --git a/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/TraceWebFilter.java b/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/TraceWebFilter.java
index 57f0320d6..6768bd452 100644
--- a/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/TraceWebFilter.java
+++ b/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/TraceWebFilter.java
@@ -133,7 +133,8 @@ public class TraceWebFilter implements WebFilter, Ordered {
 								.map(c -> c.put(CONTEXT_ERROR, t)))
 						.flatMap(c -> {
 							//reactivate span from context
-							Span span = c.getOrDefault(Span.class, tracer().nextSpan().start());
+							SpanAndScope spanAndScope = c.getOrDefault(SpanAndScope.class, defaultSpanAndScope());
+							Span span = spanAndScope.span;
 							Mono<Void> continuation;
 							Throwable t = null;
 							if (c.hasKey(CONTEXT_ERROR)) {
@@ -151,12 +152,14 @@ public class TraceWebFilter implements WebFilter, Ordered {
 							}
 							addResponseTagsForSpanWithoutParent(exchange, response, span);
 							handler().handleSend(response, t, span);
+							spanAndScope.scope.close();
 							return continuation;
 						})
 						.subscriberContext(c -> {
 							Span span;
-							if (c.hasKey(Span.class)) {
-								Span parent = c.get(Span.class);
+							if (c.hasKey(SpanAndScope.class)) {
+								SpanAndScope spanAndScope = c.get(SpanAndScope.class);
+								Span parent = spanAndScope.span;
 								span = tracer()
 										.nextSpan(TraceContextOrSamplingFlags.create(parent.context()))
 										.start();
@@ -184,10 +187,15 @@ public class TraceWebFilter implements WebFilter, Ordered {
 									}
 								}
 							}
-							return c.put(Span.class, span);
+							return c.put(SpanAndScope.class, new SpanAndScope(span, tracer().withSpanInScope(span)));
 						}));
 	}
 
+	private SpanAndScope defaultSpanAndScope() {
+		Span defaultSpan = tracer().nextSpan().start();
+		return new SpanAndScope(defaultSpan, tracer().withSpanInScope(defaultSpan));
+	}
+
 	private void addResponseTagsForSpanWithoutParent(ServerWebExchange exchange,
 			ServerHttpResponse response, Span span) {
 		if (spanWithoutParent(exchange) && response.getStatusCode() != null
@@ -221,6 +229,22 @@ public class TraceWebFilter implements WebFilter, Ordered {
 		}
 	}
 
+	class SpanAndScope {
+
+		final Span span;
+		final Tracer.SpanInScope scope;
+
+		SpanAndScope(Span span, Tracer.SpanInScope scope) {
+			this.span = span;
+			this.scope = scope;
+		}
+
+		SpanAndScope() {
+			this.span = null;
+			this.scope = null;
+		}
+	}
+
 	private void addClassNameTag(Object handler, Span span) {
 		String className;
 		if (handler instanceof HandlerMethod) {
diff --git a/spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/TraceWebFluxTests.java b/spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/TraceWebFluxTests.java
index 942cbcdf8..127b373f2 100644
--- a/spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/TraceWebFluxTests.java
+++ b/spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/TraceWebFluxTests.java
@@ -1,14 +1,10 @@
 package org.springframework.cloud.sleuth.instrument.web;
 
 import brave.sampler.Sampler;
-import reactor.core.publisher.Flux;
-import reactor.core.publisher.Hooks;
-import reactor.core.publisher.Mono;
-import reactor.core.scheduler.Schedulers;
-import org.assertj.core.api.BDDAssertions;
 import org.awaitility.Awaitility;
 import org.junit.BeforeClass;
 import org.junit.Test;
+import org.slf4j.MDC;
 import org.springframework.boot.WebApplicationType;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.security.reactive.ReactiveSecurityAutoConfiguration;
@@ -24,6 +20,12 @@ import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.reactive.function.client.ClientResponse;
 import org.springframework.web.reactive.function.client.WebClient;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Hooks;
+import reactor.core.publisher.Mono;
+import reactor.core.scheduler.Schedulers;
+
+import static org.assertj.core.api.BDDAssertions.then;
 
 public class TraceWebFluxTests {
 
@@ -47,10 +49,10 @@ public class TraceWebFluxTests {
 
 		Awaitility.await().untilAsserted(() -> {
 			ClientResponse response = exchange.block();
-			BDDAssertions.then(response.statusCode().value()).isEqualTo(200);
+			then(response.statusCode().value()).isEqualTo(200);
 		});
-		BDDAssertions.then(accumulator.getSpans()).hasSize(1);
-		BDDAssertions.then(accumulator.getSpans().get(0).tags())
+		then(accumulator.getSpans()).hasSize(1);
+		then(accumulator.getSpans().get(0).tags())
 				.containsEntry("mvc.controller.method", "successful")
 				.containsEntry("mvc.controller.class", "Controller2");
 	}
@@ -80,8 +82,11 @@ public class TraceWebFluxTests {
 
 	@RestController
 	static class Controller2 {
+
 		@GetMapping("/api/c2/{id}")
 		public Flux<String> successful(@PathVariable Long id) {
+			// #786
+			then(MDC.get("X-B3-TraceId")).isNotEmpty();
 			return Flux.just(id.toString());
 		}
 	}