diff --git a/mirai-core-api/src/commonMain/kotlin/message/data/Image.kt b/mirai-core-api/src/commonMain/kotlin/message/data/Image.kt
index 75163ff7cd..c84286ba90 100644
--- a/mirai-core-api/src/commonMain/kotlin/message/data/Image.kt
+++ b/mirai-core-api/src/commonMain/kotlin/message/data/Image.kt
@@ -306,7 +306,6 @@ public interface Image : Message, MessageContent, CodableMessage {
          * @see Image.imageType
          */
         public var type: ImageType = ImageType.UNKNOWN
-
         /**
          * @see Image.width
          */
@@ -324,6 +323,9 @@ public interface Image : Message, MessageContent, CodableMessage {
 
 
         public fun build(): Image {
+            if (type == ImageType.UNKNOWN) {
+                type = ImageType.match(imageId.split(".").last())
+            }
             @OptIn(MiraiInternalApi::class)
             return InternalImageProtocol.instance.createImage(
                 imageId = imageId,
diff --git a/mirai-core/src/commonTest/kotlin/message/ImageBuilderTest.kt b/mirai-core/src/commonTest/kotlin/message/ImageBuilderTest.kt
index 0769439069..1efef4a2a3 100644
--- a/mirai-core/src/commonTest/kotlin/message/ImageBuilderTest.kt
+++ b/mirai-core/src/commonTest/kotlin/message/ImageBuilderTest.kt
@@ -19,6 +19,10 @@ import kotlin.test.assertEquals
 internal class ImageBuilderTest : AbstractTest() {
     companion object {
         private const val IMAGE_ID = "{01E9451B-70ED-EAE3-B37C-101F1EEBF5B5}.jpg"
+        private const val IMAGE_ID_PNG = "{01E9451B-70ED-EAE3-B37C-101F1EEBF5B5}.png"
+        private const val IMAGE_ID_BMP = "{01E9451B-70ED-EAE3-B37C-101F1EEBF5B5}.bmp"
+        private const val IMAGE_ID_GIF = "{01E9451B-70ED-EAE3-B37C-101F1EEBF5B5}.gif"
+        private const val IMAGE_ID_UNKNOW = "/01E9451B-70ED-EAE3-B37C-101F1EEBF5B5"
     }
 
     @Test
@@ -57,6 +61,50 @@ internal class ImageBuilderTest : AbstractTest() {
             assertEquals(0, width)
             assertEquals(0, height)
             assertEquals(0, size)
+            assertEquals(ImageType.JPG, imageType)
+            assertEquals(false, isEmoji)
+        }
+    }
+
+    @Test
+    fun imageType() {
+        Image(IMAGE_ID).run {
+            assertEquals(IMAGE_ID, imageId)
+            assertEquals(0, width)
+            assertEquals(0, height)
+            assertEquals(0, size)
+            assertEquals(ImageType.JPG, imageType)
+            assertEquals(false, isEmoji)
+        }
+        Image(IMAGE_ID_PNG).run {
+            assertEquals(IMAGE_ID_PNG, imageId)
+            assertEquals(0, width)
+            assertEquals(0, height)
+            assertEquals(0, size)
+            assertEquals(ImageType.PNG, imageType)
+            assertEquals(false, isEmoji)
+        }
+        Image(IMAGE_ID_BMP).run {
+            assertEquals(IMAGE_ID_BMP, imageId)
+            assertEquals(0, width)
+            assertEquals(0, height)
+            assertEquals(0, size)
+            assertEquals(ImageType.BMP, imageType)
+            assertEquals(false, isEmoji)
+        }
+        Image(IMAGE_ID_GIF).run {
+            assertEquals(IMAGE_ID_GIF, imageId)
+            assertEquals(0, width)
+            assertEquals(0, height)
+            assertEquals(0, size)
+            assertEquals(ImageType.GIF, imageType)
+            assertEquals(false, isEmoji)
+        }
+        Image(IMAGE_ID_UNKNOW).run {
+            assertEquals(IMAGE_ID_UNKNOW, imageId)
+            assertEquals(0, width)
+            assertEquals(0, height)
+            assertEquals(0, size)
             assertEquals(ImageType.UNKNOWN, imageType)
             assertEquals(false, isEmoji)
         }
@@ -71,7 +119,7 @@ internal class ImageBuilderTest : AbstractTest() {
             assertEquals(0, width)
             assertEquals(0, height)
             assertEquals(0, size)
-            assertEquals(ImageType.UNKNOWN, imageType)
+            assertEquals(ImageType.JPG, imageType)
             assertEquals(false, isEmoji)
         }
         Image.fromId(IMAGE_ID).run {
@@ -79,7 +127,7 @@ internal class ImageBuilderTest : AbstractTest() {
             assertEquals(0, width)
             assertEquals(0, height)
             assertEquals(0, size)
-            assertEquals(ImageType.UNKNOWN, imageType)
+            assertEquals(ImageType.JPG, imageType)
             assertEquals(false, isEmoji)
         }
         Image(IMAGE_ID).run {
@@ -87,7 +135,7 @@ internal class ImageBuilderTest : AbstractTest() {
             assertEquals(0, width)
             assertEquals(0, height)
             assertEquals(0, size)
-            assertEquals(ImageType.UNKNOWN, imageType)
+            assertEquals(ImageType.JPG, imageType)
             assertEquals(false, isEmoji)
         }
         Image(IMAGE_ID) {
diff --git a/mirai-core/src/commonTest/kotlin/message/protocol/impl/LongMessageProtocolTest.kt b/mirai-core/src/commonTest/kotlin/message/protocol/impl/LongMessageProtocolTest.kt
index 5010e119c4..5feb3baf33 100644
--- a/mirai-core/src/commonTest/kotlin/message/protocol/impl/LongMessageProtocolTest.kt
+++ b/mirai-core/src/commonTest/kotlin/message/protocol/impl/LongMessageProtocolTest.kt
@@ -76,7 +76,7 @@ internal class LongMessageProtocolTest : AbstractMessageProtocolTest() {
                             <?xml version='1.0' encoding='UTF-8' standalone='yes' ?>
                             <msg serviceID="35" templateID="1" action="viewMultiMsg"
                                  brief="testqGnJ1R..."
-                                 m_resid="(size=1)DBD2AB20196EEB631C95DEF40E20C709"
+                                 m_resid="(size=1)6C6FD4AEC362AA8E54058A27B422FA42"
                                  m_fileName="160023" sourceMsgId="0" url=""
                                  flag="3" adverSign="0" multiMsgFlag="1">
                                 <item layout="1">
@@ -86,7 +86,7 @@ internal class LongMessageProtocolTest : AbstractMessageProtocolTest() {
                                 </item>
                                 <source name="聊天记录" icon="" action="" appid="-1"/>
                             </msg>
-                """.trimIndent(), "(size=1)DBD2AB20196EEB631C95DEF40E20C709"
+                """.trimIndent(), "(size=1)6C6FD4AEC362AA8E54058A27B422FA42"
                     ) + IgnoreLengthCheck + ForceAsLongMessage, context.currentMessageChain
                 )
             }