diff --git a/storage/filesystem/fat/source/FATFileSystem.cpp b/storage/filesystem/fat/source/FATFileSystem.cpp
index 3006a24530e..98fa2a5f981 100644
--- a/storage/filesystem/fat/source/FATFileSystem.cpp
+++ b/storage/filesystem/fat/source/FATFileSystem.cpp
@@ -755,6 +755,7 @@ int FATFileSystem::file_truncate(fs_file_t file, off_t length)
         return fat_error_remap(res);
     }
 
+    unlock();
     return 0;
 }