diff --git a/src/mwindow.c b/src/mwindow.c
index ee693e4a0..64eba01b9 100644
--- a/src/mwindow.c
+++ b/src/mwindow.c
@@ -293,28 +293,23 @@ int git_mwindow_file_register(git_mwindow_file *mwf)
 	return ret;
 }
 
-int git_mwindow_file_deregister(git_mwindow_file *mwf)
+void git_mwindow_file_deregister(git_mwindow_file *mwf)
 {
 	git_mwindow_ctl *ctl = &mem_ctl;
 	git_mwindow_file *cur;
 	unsigned int i;
 
-	if (git_mutex_lock(&git__mwindow_mutex)) {
-		giterr_set(GITERR_THREAD, "unable to lock mwindow mutex");
-		return -1;
-	}
+	if (git_mutex_lock(&git__mwindow_mutex))
+		return;
 
 	git_vector_foreach(&ctl->windowfiles, i, cur) {
 		if (cur == mwf) {
 			git_vector_remove(&ctl->windowfiles, i);
 			git_mutex_unlock(&git__mwindow_mutex);
-			return 0;
+			return;
 		}
 	}
 	git_mutex_unlock(&git__mwindow_mutex);
-
-	giterr_set(GITERR_ODB, "Failed to find the memory window file to deregister");
-	return -1;
 }
 
 void git_mwindow_close(git_mwindow **window)
diff --git a/src/mwindow.h b/src/mwindow.h
index c5aeaf77b..dc58a8605 100644
--- a/src/mwindow.h
+++ b/src/mwindow.h
@@ -39,7 +39,7 @@ int git_mwindow_contains(git_mwindow *win, git_off_t offset);
 void git_mwindow_free_all(git_mwindow_file *mwf);
 unsigned char *git_mwindow_open(git_mwindow_file *mwf, git_mwindow **cursor, git_off_t offset, size_t extra, unsigned int *left);
 int git_mwindow_file_register(git_mwindow_file *mwf);
-int git_mwindow_file_deregister(git_mwindow_file *mwf);
+void git_mwindow_file_deregister(git_mwindow_file *mwf);
 void git_mwindow_close(git_mwindow **w_cursor);
 
 #endif