diff --git a/src/main/kotlin/assimp/Importer.kt b/src/main/kotlin/assimp/Importer.kt
index 702915d..0716fd3 100644
--- a/src/main/kotlin/assimp/Importer.kt
+++ b/src/main/kotlin/assimp/Importer.kt
@@ -300,6 +300,7 @@ constructor() {
 
         // Get file size for progress handler
         val fileSize = ioSystem.open(file).length.i
+        ioSystem.close()
 
         // Dispatch the reading to the worker class for this format
         val desc = imp.info
diff --git a/src/main/kotlin/assimp/format/obj/ObjFileImporter.kt b/src/main/kotlin/assimp/format/obj/ObjFileImporter.kt
index dce2e37..5de9d82 100644
--- a/src/main/kotlin/assimp/format/obj/ObjFileImporter.kt
+++ b/src/main/kotlin/assimp/format/obj/ObjFileImporter.kt
@@ -45,6 +45,8 @@ class ObjFileImporter : BaseImporter() {
 
         // And create the proper return structures out of it
         createDataFromImport(parser.model, scene, ioSystem)
+
+        ioSystem.close()
     }
 
     /**  Create the data from parsed obj-file   */