diff --git a/spring-test/src/main/java/org/springframework/test/web/servlet/request/AbstractMockHttpServletRequestBuilder.java b/spring-test/src/main/java/org/springframework/test/web/servlet/request/AbstractMockHttpServletRequestBuilder.java
index bcc47e2b491..8d688e7bfd4 100644
--- a/spring-test/src/main/java/org/springframework/test/web/servlet/request/AbstractMockHttpServletRequestBuilder.java
+++ b/spring-test/src/main/java/org/springframework/test/web/servlet/request/AbstractMockHttpServletRequestBuilder.java
@@ -826,7 +826,7 @@ public final MockHttpServletRequest buildRequest(ServletContext servletContext)
 		addRequestParams(request, UriComponentsBuilder.fromUri(uri).build().getQueryParams());
 
 		this.parameters.forEach((name, values) ->
-				request.setParameter(name, values.toArray(new String[0])));
+				request.addParameter(name, values.toArray(new String[0])));
 
 		if (!this.formFields.isEmpty()) {
 			if (this.content != null && this.content.length > 0) {
diff --git a/spring-test/src/test/java/org/springframework/test/web/servlet/request/MockHttpServletRequestBuilderTests.java b/spring-test/src/test/java/org/springframework/test/web/servlet/request/MockHttpServletRequestBuilderTests.java
index f62cce7c551..6ba183d9aa4 100644
--- a/spring-test/src/test/java/org/springframework/test/web/servlet/request/MockHttpServletRequestBuilderTests.java
+++ b/spring-test/src/test/java/org/springframework/test/web/servlet/request/MockHttpServletRequestBuilderTests.java
@@ -273,6 +273,15 @@ void queryParameterWithoutValues() {
 		assertThat(request.getParameterMap().get("foo")).containsExactly();
 	}
 
+	@Test
+	void queryParametersWithUriAndQueryParam() {
+		this.builder = new MockHttpServletRequestBuilder(GET).uri("/path?param1=value1");
+		this.builder.queryParam("param1", "value2");
+		MockHttpServletRequest request = this.builder.buildRequest(this.servletContext);
+
+		assertThat(request.getParameterMap().get("param1")).containsExactly("value1", "value2");
+	}
+
 	@Test
 	void queryParameterMap() {
 		this.builder = new MockHttpServletRequestBuilder(GET).uri("/");