diff --git a/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration.java b/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration.java
index b3fa832431..3d9ccdfa3e 100644
--- a/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration.java
+++ b/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration.java
@@ -426,6 +426,7 @@ public class WebMvcAutoConfiguration {
 			customizer.accept(registration);
 			registration.setCachePeriod(getSeconds(this.resourceProperties.getCache().getPeriod()));
 			registration.setCacheControl(this.resourceProperties.getCache().getCachecontrol().toHttpCacheControl());
+			registration.setUseLastModified(this.resourceProperties.getCache().isUseLastModified());
 			customizeResourceHandlerRegistration(registration);
 		}
 
diff --git a/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfigurationTests.java b/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfigurationTests.java
index 3e929144d2..5de65c40be 100644
--- a/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfigurationTests.java
+++ b/spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfigurationTests.java
@@ -1009,7 +1009,7 @@ class WebMvcAutoConfigurationTests {
 			Consumer<ResourceHttpRequestHandler> handlerConsumer) {
 		Map<String, Object> handlerMap = getHandlerMap(context.getBean("resourceHandlerMapping", HandlerMapping.class));
 		assertThat(handlerMap).hasSize(2);
-		for (Object handler : handlerMap.keySet()) {
+		for (Object handler : handlerMap.values()) {
 			if (handler instanceof ResourceHttpRequestHandler) {
 				handlerConsumer.accept((ResourceHttpRequestHandler) handler);
 			}