diff --git a/include/hooks.h b/include/hooks.h
index 1db393d..ab562aa 100644
--- a/include/hooks.h
+++ b/include/hooks.h
@@ -35,19 +35,19 @@ typedef enum {
     POST_EVERYTHING,
 } e_report_status;
 
-typedef void (*f_report_hook)(void *);
+typedef void (*f_report_hook)();
 
 # define HOOK_IDENTIFIER_(Suffix) HOOK_IDENTIFIER__(__LINE__, Suffix)
 # define HOOK_IDENTIFIER__(Line, Suffix) HOOK_IDENTIFIER___(Line, Suffix)
 # define HOOK_IDENTIFIER___(Line, Suffix) hook_l ## Line ## _ ## Suffix
 
 # define HOOK_PROTOTYPE_                                                       \
-    void HOOK_IDENTIFIER_(impl)(UNUSED void *data)
+    void HOOK_IDENTIFIER_(impl)
 
 # define ReportHook(Kind)                                                      \
-    HOOK_PROTOTYPE_;                                                           \
+    HOOK_PROTOTYPE_();                                                         \
     SECTION_("criterion_hooks_" #Kind)                                         \
-    const f_report_hook HOOK_IDENTIFIER_(func) = HOOK_IDENTIFIER_(impl);      \
+    const f_report_hook HOOK_IDENTIFIER_(func) = HOOK_IDENTIFIER_(impl);       \
     HOOK_PROTOTYPE_
 
 #endif /* !CRITERION_HOOKS_H_ */
diff --git a/samples/simple.c b/samples/simple.c
index 7507483..01fb583 100644
--- a/samples/simple.c
+++ b/samples/simple.c
@@ -13,23 +13,19 @@ Test(misc, simple) {
     expect(1);
 }
 
-ReportHook(PRE_INIT) {
-    struct criterion_test *test = data;
-
+ReportHook(PRE_INIT)(struct criterion_test *test) {
     printf("testing %s in category %s\n", test->name, test->category);
 }
 
-ReportHook(POST_TEST) {
-    struct criterion_test_stats *stats = data;
-
+ReportHook(POST_TEST)(struct criterion_test_stats *stats) {
     printf("Asserts: [%d passed, %d failed, %d total]\n",
             stats->passed, stats->failed, stats->passed + stats->failed);
 }
 
-ReportHook(PRE_EVERYTHING) {
+ReportHook(PRE_EVERYTHING)() {
     puts("criterion_init");
 }
 
-ReportHook(POST_EVERYTHING) {
+ReportHook(POST_EVERYTHING)() {
     puts("criterion_fini");
 }
diff --git a/src/report.c b/src/report.c
index 2644566..19af069 100644
--- a/src/report.c
+++ b/src/report.c
@@ -45,22 +45,18 @@ IMPL_CALL_REPORT_HOOKS(POST_TEST);
 IMPL_CALL_REPORT_HOOKS(POST_FINI);
 IMPL_CALL_REPORT_HOOKS(POST_EVERYTHING);
 
-ReportHook(PRE_INIT) {
-    struct criterion_test *test = data;
-
+ReportHook(PRE_INIT)(struct criterion_test *test) {
     fprintf(stderr, "%s::%s: RUNNING\n", test->category, test->name);
 }
 
-ReportHook(POST_TEST) {
-    struct criterion_test_stats *stats = data;
-
+ReportHook(POST_TEST)(struct criterion_test_stats *stats) {
     int success = stats->failed == 0;
 
     fprintf(stderr, "%s::%s: %s\n", stats->test->category, stats->test->name, success ? "SUCCESS" : "FAILURE");
 }
 
-ReportHook(PRE_TEST) {}
-ReportHook(POST_FINI) {}
+ReportHook(PRE_TEST)() {}
+ReportHook(POST_FINI)() {}
 
-ReportHook(PRE_EVERYTHING) {}
-ReportHook(POST_EVERYTHING) {}
+ReportHook(PRE_EVERYTHING)() {}
+ReportHook(POST_EVERYTHING)() {}