diff --git a/xtest.h b/xtest.h
index 5808212..3341c33 100644
--- a/xtest.h
+++ b/xtest.h
@@ -9,9 +9,9 @@
 #include <stdio.h>
 #include <string.h>
 
-typedef void (*xtest_test_fn)(void *, void **);
-typedef void (*xtest_setup_fn)(void **);
-typedef void (*xtest_teardown_fn)(void *);
+typedef void (*xtest_test_fn)(void * fixture, void ** params);
+typedef void (*xtest_setup_fn)(void ** fixture);
+typedef void (*xtest_teardown_fn)(void * fixture);
 
 typedef struct xtest_param_s xtest_param;