diff --git a/src/Processors/Formats/Impl/MsgPackRowOutputFormat.cpp b/src/Processors/Formats/Impl/MsgPackRowOutputFormat.cpp
index 7c5e2c5b522..cef7b001505 100644
--- a/src/Processors/Formats/Impl/MsgPackRowOutputFormat.cpp
+++ b/src/Processors/Formats/Impl/MsgPackRowOutputFormat.cpp
@@ -85,7 +85,6 @@ void MsgPackRowOutputFormat::serializeField(const IColumn & column, DataTypePtr
             packer.pack_uint64(assert_cast<const DataTypeDateTime64::ColumnType &>(column).getElement(row_num));
             return;
         }
-        case TypeIndex::FixedString: [[fallthrough]];
         case TypeIndex::String:
         {
             const StringRef & string = assert_cast<const ColumnString &>(column).getDataAt(row_num);
@@ -93,6 +92,13 @@ void MsgPackRowOutputFormat::serializeField(const IColumn & column, DataTypePtr
             packer.pack_str_body(string.data, string.size);
             return;
         }
+        case TypeIndex::FixedString:
+        {
+            const StringRef & string = assert_cast<const ColumnFixedString &>(column).getDataAt(row_num);
+            packer.pack_str(string.size);
+            packer.pack_str_body(string.data, string.size);
+            return;
+        }
         case TypeIndex::Array:
         {
             auto nested_type = assert_cast<const DataTypeArray &>(*data_type).getNestedType();