diff --git a/spring-test/src/main/java/org/springframework/mock/web/MockPart.java b/spring-test/src/main/java/org/springframework/mock/web/MockPart.java
index 4e0a1d365c02..897891ff10a9 100644
--- a/spring-test/src/main/java/org/springframework/mock/web/MockPart.java
+++ b/spring-test/src/main/java/org/springframework/mock/web/MockPart.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -63,24 +63,21 @@ public MockPart(String name, @Nullable byte[] content) {
 	 * @see #getHeaders()
 	 */
 	public MockPart(String name, @Nullable String filename, @Nullable byte[] content) {
-		Assert.hasLength(name, "'name' must not be empty");
-		this.name = name;
-		this.filename = filename;
-		this.content = (content != null ? content : new byte[0]);
-		this.headers.setContentDispositionFormData(name, filename);
+		this(name, filename, content, null);
 	}
 
 	/**
-	 * Constructor for a part with a filename, byte[] content and MediaType mediaType.
+	 * Constructor for a part with a filename, byte[] content, and content type.
+	 * @since 6.1.2
 	 * @see #getHeaders()
 	 */
-	public MockPart(String name, @Nullable String filename, @Nullable byte[] content, @Nullable MediaType mediaType) {
+	public MockPart(String name, @Nullable String filename, @Nullable byte[] content, @Nullable MediaType contentType) {
 		Assert.hasLength(name, "'name' must not be empty");
 		this.name = name;
 		this.filename = filename;
 		this.content = (content != null ? content : new byte[0]);
 		this.headers.setContentDispositionFormData(name, filename);
-		this.headers.setContentType(mediaType);
+		this.headers.setContentType(contentType);
 	}
 
 
diff --git a/spring-test/src/test/java/org/springframework/mock/web/MockMultipartHttpServletRequestTests.java b/spring-test/src/test/java/org/springframework/mock/web/MockMultipartHttpServletRequestTests.java
index 6905183737e6..82ecd7858bbf 100644
--- a/spring-test/src/test/java/org/springframework/mock/web/MockMultipartHttpServletRequestTests.java
+++ b/spring-test/src/test/java/org/springframework/mock/web/MockMultipartHttpServletRequestTests.java
@@ -68,8 +68,7 @@ void mockMultiPartHttpServletRequestWithMixedData() {
 		MockMultipartHttpServletRequest request = new MockMultipartHttpServletRequest();
 		request.addFile(new MockMultipartFile("file", "myOrigFilename", MediaType.TEXT_PLAIN_VALUE, "myContent2".getBytes()));
 
-		MockPart metadataPart = new MockPart("metadata", "{\"foo\": \"bar\"}".getBytes());
-		metadataPart.getHeaders().setContentType(MediaType.APPLICATION_JSON);
+		MockPart metadataPart = new MockPart("metadata", null, "{\"foo\": \"bar\"}".getBytes(), MediaType.APPLICATION_JSON);
 		request.addPart(metadataPart);
 
 		HttpHeaders fileHttpHeaders = request.getMultipartHeaders("file");
diff --git a/spring-web/src/testFixtures/java/org/springframework/web/testfixture/servlet/MockPart.java b/spring-web/src/testFixtures/java/org/springframework/web/testfixture/servlet/MockPart.java
index ac1ce65d0ef0..e9ca45c033df 100644
--- a/spring-web/src/testFixtures/java/org/springframework/web/testfixture/servlet/MockPart.java
+++ b/spring-web/src/testFixtures/java/org/springframework/web/testfixture/servlet/MockPart.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,7 +34,7 @@
  *
  * @author Rossen Stoyanchev
  * @author Juergen Hoeller
- * @since 3.1
+ * @since 4.3.12
  * @see MockHttpServletRequest#addPart
  * @see MockMultipartFile
  */
@@ -63,11 +63,21 @@ public MockPart(String name, @Nullable byte[] content) {
 	 * @see #getHeaders()
 	 */
 	public MockPart(String name, @Nullable String filename, @Nullable byte[] content) {
+		this(name, filename, content, null);
+	}
+
+	/**
+	 * Constructor for a part with a filename, byte[] content, and content type.
+	 * @since 6.1.2
+	 * @see #getHeaders()
+	 */
+	public MockPart(String name, @Nullable String filename, @Nullable byte[] content, @Nullable MediaType contentType) {
 		Assert.hasLength(name, "'name' must not be empty");
 		this.name = name;
 		this.filename = filename;
 		this.content = (content != null ? content : new byte[0]);
 		this.headers.setContentDispositionFormData(name, filename);
+		this.headers.setContentType(contentType);
 	}