diff --git a/pkg/fs/fs-multipart.go b/pkg/fs/fs-multipart.go
index 1ee6c4754..37a6a262f 100644
--- a/pkg/fs/fs-multipart.go
+++ b/pkg/fs/fs-multipart.go
@@ -435,7 +435,7 @@ func (fs Filesystem) CompleteMultipartUpload(bucket, object, uploadID string, da
 	}
 	contentType := "application/octet-stream"
 	if objectExt := filepath.Ext(objectPath); objectExt != "" {
-		contentType = contentdb.MustLookup(strings.TrimPrefix(objectExt, "."))
+		contentType = contentdb.MustLookup(strings.ToLower(strings.TrimPrefix(objectExt, ".")))
 	}
 	newObject := ObjectMetadata{
 		Bucket:      bucket,
diff --git a/pkg/fs/fs-object.go b/pkg/fs/fs-object.go
index b4b14bf44..471a218cf 100644
--- a/pkg/fs/fs-object.go
+++ b/pkg/fs/fs-object.go
@@ -155,7 +155,7 @@ func getMetadata(rootPath, bucket, object string) (ObjectMetadata, *probe.Error)
 		object = sanitizeWindowsPath(object)
 	}
 	if objectExt := filepath.Ext(object); objectExt != "" {
-		contentType = contentdb.MustLookup(strings.TrimPrefix(objectExt, "."))
+		contentType = contentdb.MustLookup(strings.ToLower(strings.TrimPrefix(objectExt, ".")))
 	}
 	metadata := ObjectMetadata{
 		Bucket:      bucket,
@@ -285,7 +285,7 @@ func (fs Filesystem) CreateObject(bucket, object, expectedMD5Sum string, size in
 	}
 	contentType := "application/octet-stream"
 	if objectExt := filepath.Ext(objectPath); objectExt != "" {
-		contentType = contentdb.MustLookup(strings.TrimPrefix(objectExt, "."))
+		contentType = contentdb.MustLookup(strings.ToLower(strings.TrimPrefix(objectExt, ".")))
 	}
 	newObject := ObjectMetadata{
 		Bucket:      bucket,