diff --git a/today-web/src/main/java/cn/taketoday/http/codec/multipart/PartEventHttpMessageReader.java b/today-web/src/main/java/cn/taketoday/http/codec/multipart/PartEventHttpMessageReader.java
index afb2b7cce1..f237de5108 100644
--- a/today-web/src/main/java/cn/taketoday/http/codec/multipart/PartEventHttpMessageReader.java
+++ b/today-web/src/main/java/cn/taketoday/http/codec/multipart/PartEventHttpMessageReader.java
@@ -191,7 +191,14 @@ private boolean tooManyParts(AtomicInteger partCount) {
   private Publisher<? extends PartEvent> createEvents(HttpHeaders headers, Flux<MultipartParser.BodyToken> bodyTokens) {
     if (MultipartUtils.isFormField(headers)) {
       Flux<DataBuffer> contents = bodyTokens.map(MultipartParser.BodyToken::getBuffer);
-      int maxSize = (int) Math.min(this.maxInMemorySize, this.maxPartSize);
+      int maxSize;
+      if (this.maxPartSize == -1) {
+        maxSize = this.maxInMemorySize;
+      }
+      else {
+        // maxInMemorySize is an int, so we can safely cast the long result of Math.min
+        maxSize = (int) Math.min(this.maxInMemorySize, this.maxPartSize);
+      }
       return DataBufferUtils.join(contents, maxSize)
               .map(content -> {
                 String value = content.toString(MultipartUtils.charset(headers));
@@ -222,8 +229,12 @@ private Publisher<? extends PartEvent> createEvents(HttpHeaders headers, Flux<Mu
   }
 
   private boolean tooLarge(AtomicLong partSize, DataBuffer buffer) {
-    long size = partSize.addAndGet(buffer.readableByteCount());
-    return this.maxPartSize > 0 && size > this.maxPartSize;
+    if (this.maxPartSize != -1) {
+      long size = partSize.addAndGet(buffer.readableByteCount());
+      return size > this.maxPartSize;
+    }
+    else {
+      return false;
+    }
   }
-
 }
diff --git a/today-web/src/test/java/cn/taketoday/http/codec/multipart/PartEventHttpMessageReaderTests.java b/today-web/src/test/java/cn/taketoday/http/codec/multipart/PartEventHttpMessageReaderTests.java
index 5a49fa4ade..c4e2d30d32 100644
--- a/today-web/src/test/java/cn/taketoday/http/codec/multipart/PartEventHttpMessageReaderTests.java
+++ b/today-web/src/test/java/cn/taketoday/http/codec/multipart/PartEventHttpMessageReaderTests.java
@@ -17,7 +17,6 @@
 
 package cn.taketoday.http.codec.multipart;
 
-import org.assertj.core.api.AssertionsForClassTypes;
 import org.junit.jupiter.api.Test;
 
 import java.nio.charset.StandardCharsets;
@@ -46,6 +45,7 @@
 import static java.util.Collections.emptyMap;
 import static java.util.Collections.singletonMap;
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.AssertionsForClassTypes.entry;
 
 /**
  * @author <a href="/TAKETODAY">Harry Yang</a>
@@ -146,8 +146,8 @@ public void noBody() {
     Flux<PartEvent> result = this.reader.read(forClass(PartEvent.class), request, emptyMap());
 
     StepVerifier.create(result)
-            .assertNext(form(headers -> assertThat(headers).contains(AssertionsForClassTypes.entry("Part", List.of("1"))), ""))
-            .assertNext(data(headers -> assertThat(headers).contains(AssertionsForClassTypes.entry("Part", List.of("2"))), bodyText("a"), true))
+            .assertNext(form(headers -> assertThat(headers).contains(entry("Part", List.of("1"))), ""))
+            .assertNext(data(headers -> assertThat(headers).contains(entry("Part", List.of("2"))), bodyText("a"), true))
             .verifyComplete();
   }
 
@@ -258,7 +258,21 @@ void partSizeTooLarge() {
             .assertNext(data(headersFormField("text2"), bodyText("b"), true))
             .expectError(DataBufferLimitException.class)
             .verify();
+  }
+
+  @Test
+  void formPartTooLarge() {
+    MockServerHttpRequest request = createRequest(
+            new ClassPathResource("simple.multipart", getClass()), "simple-boundary");
+
+    PartEventHttpMessageReader reader = new PartEventHttpMessageReader();
+    reader.setMaxInMemorySize(40);
+
+    Flux<PartEvent> result = reader.read(forClass(PartEvent.class), request, emptyMap());
 
+    StepVerifier.create(result)
+            .expectError(DataBufferLimitException.class)
+            .verify();
   }
 
   @Test