diff --git a/tests/incremental/11-restart/11-paper-example.c b/tests/incremental/11-restart/11-paper-example.c
index e16d273f5f..d7a569b558 100644
--- a/tests/incremental/11-restart/11-paper-example.c
+++ b/tests/incremental/11-restart/11-paper-example.c
@@ -3,7 +3,7 @@
 
 pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
 
-int (*fp)() = NULL;
+int (*fp)(void) = NULL;
 
 int bad() {
     return -1;
diff --git a/tests/regression/00-sanity/15-unused_arg.c b/tests/regression/00-sanity/15-unused_arg.c
index a7dc6970e6..6587a0b9e4 100644
--- a/tests/regression/00-sanity/15-unused_arg.c
+++ b/tests/regression/00-sanity/15-unused_arg.c
@@ -4,9 +4,9 @@ void f() {
   glob++; // NOWARN!
 }
 
-void (*fptr) = f;
+void (*fptr)(void) = f;
 
-int g(void (*ptr)()) {
+int g(void (*ptr)(void)) {
   return 0;
 }
 
diff --git a/tests/regression/00-sanity/38-evalfunvar-dead.c b/tests/regression/00-sanity/38-evalfunvar-dead.c
index 26c779c7e6..2483e6ed4e 100644
--- a/tests/regression/00-sanity/38-evalfunvar-dead.c
+++ b/tests/regression/00-sanity/38-evalfunvar-dead.c
@@ -1,7 +1,7 @@
 #include <stdlib.h>
 
 int main() {
-  int (*fp)() = &rand;
+  int (*fp)(void) = &rand;
   abort();
   fp(); // NOWARN (No suitable function to call)
   return 0;
diff --git a/tests/regression/01-cpa/06-pointers.c b/tests/regression/01-cpa/06-pointers.c
index c70080c01e..b151a00117 100644
--- a/tests/regression/01-cpa/06-pointers.c
+++ b/tests/regression/01-cpa/06-pointers.c
@@ -8,7 +8,7 @@ int fun_5b() { return 5; }
 int main () {
   int i,j,k1,k2,k3;
   int *p, **pp;
-  int (*fp)(); //pointer to function
+  int (*fp)(void); //pointer to function
 
   // reading through pointer
   i = 5;
diff --git a/tests/regression/01-cpa/09-arrays.c b/tests/regression/01-cpa/09-arrays.c
index 07025a2a4c..c38ffb8933 100644
--- a/tests/regression/01-cpa/09-arrays.c
+++ b/tests/regression/01-cpa/09-arrays.c
@@ -18,9 +18,9 @@ int main () {
 
   int a[] = {2,2,2};
   int b[2], c[3];
-  int (*f[2])() = {fun_5, fun_6};
-  int (*g[2])() = {fun_5, fun_5b};
-  int (*fp)();
+  int (*f[2])(void) = {fun_5, fun_6};
+  int (*g[2])(void) = {fun_5, fun_5b};
+  int (*fp)(void);
   int *ip;
   int (*iap)[];
 
diff --git a/tests/regression/01-cpa/46-funptr_path.c b/tests/regression/01-cpa/46-funptr_path.c
index 8e2523ad37..e06784ef9d 100644
--- a/tests/regression/01-cpa/46-funptr_path.c
+++ b/tests/regression/01-cpa/46-funptr_path.c
@@ -16,7 +16,7 @@ void fun2() {
 int main() {
   int x = __VERIFIER_nondet_int();
 
-  void (*fp)();
+  void (*fp)(void);
 
   if (x) {
     pthread_mutex_lock(&mutex);
diff --git a/tests/regression/02-base/46-spawn-global-funptrs.c b/tests/regression/02-base/46-spawn-global-funptrs.c
index 24474a6cf3..e67a6e4145 100644
--- a/tests/regression/02-base/46-spawn-global-funptrs.c
+++ b/tests/regression/02-base/46-spawn-global-funptrs.c
@@ -9,13 +9,13 @@ void bar() {
   __goblint_check(1); // assert reachable
 }
 
-void (*funs[2])() = {
+void (*funs[2])(void) = {
   &foo,
   &bar
 };
 
 extern void magic1();
-extern void magic2(void (*funs[])());
+extern void magic2(void (*funs[])(void));
 
 int main() {
   magic1(); // invalidate funs a bit
diff --git a/tests/regression/03-practical/06-callback.c b/tests/regression/03-practical/06-callback.c
index 6cc6ab132f..0c35b155ef 100644
--- a/tests/regression/03-practical/06-callback.c
+++ b/tests/regression/03-practical/06-callback.c
@@ -9,7 +9,7 @@ void callme(void)  {
   x = 5;
 }
 
-void callfun(void (*fun)()) {
+void callfun(void (*fun)(void)) {
   fun();
   return;
 }
diff --git a/tests/regression/04-mutex/19-call_by_ptr_rc.c b/tests/regression/04-mutex/19-call_by_ptr_rc.c
index b4895bb7cf..2d4166c390 100644
--- a/tests/regression/04-mutex/19-call_by_ptr_rc.c
+++ b/tests/regression/04-mutex/19-call_by_ptr_rc.c
@@ -2,7 +2,7 @@ extern int __VERIFIER_nondet_int();
 
 #include<pthread.h>
 
-void foo(int (*callback)()) {
+void foo(int (*callback)(void)) {
   for (int i = 0; i < 10; i++) {
     if (__VERIFIER_nondet_int())
       callback();
diff --git a/tests/regression/04-mutex/21-sound_base.c b/tests/regression/04-mutex/21-sound_base.c
index 18086eb570..612eaff8de 100644
--- a/tests/regression/04-mutex/21-sound_base.c
+++ b/tests/regression/04-mutex/21-sound_base.c
@@ -6,7 +6,7 @@ int global;
 void bad() { global++; } // RACE!
 void good() { printf("Hello!"); }
 
-void (*f)() = good;
+void (*f)(void) = good;
 
 void *t_fun(void *arg) {
   f(); // RACE!
diff --git a/tests/regression/04-mutex/27-base_rc.c b/tests/regression/04-mutex/27-base_rc.c
index 68874fcc07..3e05f512c6 100644
--- a/tests/regression/04-mutex/27-base_rc.c
+++ b/tests/regression/04-mutex/27-base_rc.c
@@ -13,11 +13,11 @@ void good() {
   pthread_mutex_unlock(&gm);
 }
 
-void (*f)() = good;
+void (*f)(void) = good;
 pthread_mutex_t fm = PTHREAD_MUTEX_INITIALIZER;
 
 void *t_fun(void *arg) {
-  void (*g)();
+  void (*g)(void);
 
   pthread_mutex_lock(&fm);
   g = f; // NORACE
diff --git a/tests/regression/04-mutex/28-base_nr.c b/tests/regression/04-mutex/28-base_nr.c
index 58962d74b9..9a0325bc9a 100644
--- a/tests/regression/04-mutex/28-base_nr.c
+++ b/tests/regression/04-mutex/28-base_nr.c
@@ -13,11 +13,11 @@ void good() {
   pthread_mutex_unlock(&gm);
 }
 
-void (*f)() = good;
+void (*f)(void) = good;
 pthread_mutex_t fm = PTHREAD_MUTEX_INITIALIZER;
 
 void *t_fun(void *arg) {
-  void (*g)();
+  void (*g)(void);
 
   pthread_mutex_lock(&fm);
   g = f; // NORACE
diff --git a/tests/regression/04-mutex/29-funstruct_rc.c b/tests/regression/04-mutex/29-funstruct_rc.c
index 9b1dd0a671..a3087e7718 100644
--- a/tests/regression/04-mutex/29-funstruct_rc.c
+++ b/tests/regression/04-mutex/29-funstruct_rc.c
@@ -7,7 +7,7 @@ pthread_mutex_t B_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 struct ops {
   int (*f)(int);
-  void (*g)();
+  void (*g)(void);
 };
 
 extern void register_dev(struct ops *);
diff --git a/tests/regression/04-mutex/30-funstruct_nr.c b/tests/regression/04-mutex/30-funstruct_nr.c
index 99bc27947d..7fb075bb4e 100644
--- a/tests/regression/04-mutex/30-funstruct_nr.c
+++ b/tests/regression/04-mutex/30-funstruct_nr.c
@@ -7,7 +7,7 @@ pthread_mutex_t B_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 struct ops {
   int (*f)(int);
-  void (*g)();
+  void (*g)(void);
 };
 
 extern void register_dev(struct ops *);
diff --git a/tests/regression/04-mutex/50-funptr_rc.c b/tests/regression/04-mutex/50-funptr_rc.c
index 1bb2840c5e..f5fa217177 100644
--- a/tests/regression/04-mutex/50-funptr_rc.c
+++ b/tests/regression/04-mutex/50-funptr_rc.c
@@ -5,7 +5,7 @@
 int f1() { return 4; }
 int f2() { return 5; }
 
-int (*fp)() = f1;
+int (*fp)(void) = f1;
 
 pthread_mutex_t mutex1 = PTHREAD_MUTEX_INITIALIZER;
 pthread_mutex_t mutex2 = PTHREAD_MUTEX_INITIALIZER;
diff --git a/tests/regression/04-mutex/56-extern_call_by_ptr_rc.c b/tests/regression/04-mutex/56-extern_call_by_ptr_rc.c
index 77ba0243e6..75a0ab8da3 100644
--- a/tests/regression/04-mutex/56-extern_call_by_ptr_rc.c
+++ b/tests/regression/04-mutex/56-extern_call_by_ptr_rc.c
@@ -1,6 +1,6 @@
 #include<pthread.h>
 
-extern void foo(int (*callback)());
+extern void foo(int (*callback)(void));
 
 
 int glob;
diff --git a/tests/regression/13-privatized/95-mm-calloc.c b/tests/regression/13-privatized/95-mm-calloc.c
index 60a88379fc..6ca7dbbafa 100644
--- a/tests/regression/13-privatized/95-mm-calloc.c
+++ b/tests/regression/13-privatized/95-mm-calloc.c
@@ -3,7 +3,7 @@
 #include<stdlib.h>
 #include<stdio.h>
 struct a {
-  void (*b)();
+  void (*b)(void);
 };
 
 int g = 0;
diff --git a/tests/regression/22-partitioned_arrays/05-adapted_from_01_09_array.c b/tests/regression/22-partitioned_arrays/05-adapted_from_01_09_array.c
index 5d3dad5967..ac8717a3ea 100644
--- a/tests/regression/22-partitioned_arrays/05-adapted_from_01_09_array.c
+++ b/tests/regression/22-partitioned_arrays/05-adapted_from_01_09_array.c
@@ -19,9 +19,9 @@ int main () {
 
   int a[] = {2,2,2};
   int b[2], c[3];
-  int (*f[2])() = {fun_5, fun_6};
-  int (*g[2])() = {fun_5, fun_5b};
-  int (*fp)();
+  int (*f[2])(void) = {fun_5, fun_6};
+  int (*g[2])(void) = {fun_5, fun_5b};
+  int (*fp)(void);
   int *ip;
   int (*iap)[];
 
diff --git a/tests/regression/23-partitioned_arrays_last/05-adapted_from_01_09_array.c b/tests/regression/23-partitioned_arrays_last/05-adapted_from_01_09_array.c
index 4f5bab8103..49719e1ac9 100644
--- a/tests/regression/23-partitioned_arrays_last/05-adapted_from_01_09_array.c
+++ b/tests/regression/23-partitioned_arrays_last/05-adapted_from_01_09_array.c
@@ -19,9 +19,9 @@ int main () {
 
   int a[] = {2,2,2};
   int b[2], c[3];
-  int (*f[2])() = {fun_5, fun_6};
-  int (*g[2])() = {fun_5, fun_5b};
-  int (*fp)();
+  int (*f[2])(void) = {fun_5, fun_6};
+  int (*g[2])(void) = {fun_5, fun_5b};
+  int (*fp)(void);
   int *ip;
   int (*iap)[];
 
diff --git a/tests/regression/28-race_reach/19-callback_racing.c b/tests/regression/28-race_reach/19-callback_racing.c
index 04eaaeef4f..456660655e 100644
--- a/tests/regression/28-race_reach/19-callback_racing.c
+++ b/tests/regression/28-race_reach/19-callback_racing.c
@@ -4,7 +4,7 @@ extern int __VERIFIER_nondet_int();
 #include<pthread.h>
 #include "racemacros.h"
 
-void foo(int (*callback)()) {
+void foo(int (*callback)(void)) {
   for (int i = 0; i < 10; i++) {
     if (__VERIFIER_nondet_int())
       callback();
diff --git a/tests/regression/28-race_reach/20-callback_racefree.c b/tests/regression/28-race_reach/20-callback_racefree.c
index e41896f31a..dd78bc51b4 100644
--- a/tests/regression/28-race_reach/20-callback_racefree.c
+++ b/tests/regression/28-race_reach/20-callback_racefree.c
@@ -4,7 +4,7 @@ extern int __VERIFIER_nondet_int();
 #include<pthread.h>
 #include "racemacros.h"
 
-void foo(int (*callback)()) {
+void foo(int (*callback)(void)) {
   for (int i = 0; i < 10; i++) {
     if (__VERIFIER_nondet_int())
       callback();
diff --git a/tests/regression/28-race_reach/27-funptr_racing.c b/tests/regression/28-race_reach/27-funptr_racing.c
index 7210d0d56c..a93bc30b94 100644
--- a/tests/regression/28-race_reach/27-funptr_racing.c
+++ b/tests/regression/28-race_reach/27-funptr_racing.c
@@ -16,11 +16,11 @@ void good() {
   pthread_mutex_unlock(&gm);
 }
 
-void (*f)() = good;
+void (*f)(void) = good;
 pthread_mutex_t fm = PTHREAD_MUTEX_INITIALIZER;
 
 void *t_fun(void *arg) {
-  void (*g)();
+  void (*g)(void);
 
   pthread_mutex_lock(&fm);
   g = f;
diff --git a/tests/regression/28-race_reach/28-funptr_racefree.c b/tests/regression/28-race_reach/28-funptr_racefree.c
index f36168aaaa..a72266d4c7 100644
--- a/tests/regression/28-race_reach/28-funptr_racefree.c
+++ b/tests/regression/28-race_reach/28-funptr_racefree.c
@@ -15,11 +15,11 @@ void good() {
   pthread_mutex_unlock(&gm);
 }
 
-void (*f)() = good;
+void (*f)(void) = good;
 pthread_mutex_t fm = PTHREAD_MUTEX_INITIALIZER;
 
 void *t_fun(void *arg) {
-  void (*g)();
+  void (*g)(void);
 
   pthread_mutex_lock(&fm);
   g = f;
diff --git a/tests/regression/28-race_reach/95-deref-fun.c b/tests/regression/28-race_reach/95-deref-fun.c
index f1431d9221..d76d362134 100644
--- a/tests/regression/28-race_reach/95-deref-fun.c
+++ b/tests/regression/28-race_reach/95-deref-fun.c
@@ -1,7 +1,7 @@
 // PARAM: --enable ana.sv-comp.enabled --set ana.specification "CHECK( init(main()), LTL(G ! call(reach_error())) )"
 #include<pthread.h>
 // NOCRASH
-void foo(int (*callback)()) {
+void foo(int (*callback)(void)) {
 }
 
 int bar() {
diff --git a/tests/regression/67-interval-sets-two/18-adapted_from_01_09_array.c b/tests/regression/67-interval-sets-two/18-adapted_from_01_09_array.c
index 9e95421320..16cb9f8f20 100644
--- a/tests/regression/67-interval-sets-two/18-adapted_from_01_09_array.c
+++ b/tests/regression/67-interval-sets-two/18-adapted_from_01_09_array.c
@@ -19,9 +19,9 @@ int main () {
 
   int a[] = {2,2,2};
   int b[2], c[3];
-  int (*f[2])() = {fun_5, fun_6};
-  int (*g[2])() = {fun_5, fun_5b};
-  int (*fp)();
+  int (*f[2])(void) = {fun_5, fun_6};
+  int (*g[2])(void) = {fun_5, fun_5b};
+  int (*fp)(void);
   int *ip;
   int (*iap)[];
 
diff --git a/tests/sv-comp/cfg/free_spawn_ub_true-unreach-call.c b/tests/sv-comp/cfg/free_spawn_ub_true-unreach-call.c
index c5f565b13e..9f54cd950d 100644
--- a/tests/sv-comp/cfg/free_spawn_ub_true-unreach-call.c
+++ b/tests/sv-comp/cfg/free_spawn_ub_true-unreach-call.c
@@ -8,7 +8,7 @@ void foo()
 
 int main()
 {
-    void (*p)() = &foo;
+    void (*p)(void) = &foo;
     free(p); // TODO: free shouldn't spawn
     return 0;
 }
\ No newline at end of file
diff --git a/tests/sv-comp/cfg/free_spawn_ub_true-unreach-call.expected b/tests/sv-comp/cfg/free_spawn_ub_true-unreach-call.expected
index 0a0df994d4..0aec5cffd0 100644
--- a/tests/sv-comp/cfg/free_spawn_ub_true-unreach-call.expected
+++ b/tests/sv-comp/cfg/free_spawn_ub_true-unreach-call.expected
@@ -1,27 +1,27 @@
-┌───────────────────────────────────┐
-│                 _                 │
-└───────────────────────────────────┘
+┌─────────────────────┐
+│          _          │
+└─────────────────────┘
   │
   │ Entry main
   ▼
-┌───────────────────────────────────┐
-│                 _                 │
-└───────────────────────────────────┘
+┌─────────────────────┐
+│          _          │
+└─────────────────────┘
   │
-  │ Assign 'p = (void (*)())(& foo)'
+  │ Assign 'p = & foo'
   ▼
-┌───────────────────────────────────┐
-│                 _                 │
-└───────────────────────────────────┘
+┌─────────────────────┐
+│          _          │
+└─────────────────────┘
   │
   │ Proc 'free(p)'
   ▼
-┌───────────────────────────────────┐
-│                 _                 │
-└───────────────────────────────────┘
+┌─────────────────────┐
+│          _          │
+└─────────────────────┘
   │
   │ Ret (Some 0, main)
   ▼
-┌───────────────────────────────────┐
-│                 _                 │
-└───────────────────────────────────┘
+┌─────────────────────┐
+│          _          │
+└─────────────────────┘