diff --git a/Mod/Lib/SYSTEM.c b/Mod/Lib/SYSTEM.c
index 249f02ac..40fa94c8 100644
--- a/Mod/Lib/SYSTEM.c
+++ b/Mod/Lib/SYSTEM.c
@@ -164,16 +164,16 @@ void SYSTEM_INHERIT(SYSTEM_ADRINT *t, SYSTEM_ADRINT *t0)
 }
 
 
-void SYSTEM_ENUMP(void *adr, SYSTEM_ADRINT n, void (*P)())
+void SYSTEM_ENUMP(void *adr, SYSTEM_ADRINT n, void (*P)(void*))
 {
     while (n > 0) {
-        P((SYSTEM_ADRINT)(*((void**)(adr))));
+        P((void*)(*((void**)(adr))));
         adr = ((void**)adr) + 1;
         n--;
     }
 }
 
-void SYSTEM_ENUMR(void *adr, SYSTEM_ADRINT *typ, SYSTEM_ADRINT size, SYSTEM_ADRINT n, void (*P)())
+void SYSTEM_ENUMR(void *adr, SYSTEM_ADRINT *typ, SYSTEM_ADRINT size, SYSTEM_ADRINT n, void (*P)(void*))
 {
     SYSTEM_ADRINT *t, off;
     if (typ == 0) return; // not yet initialized
@@ -181,19 +181,19 @@ void SYSTEM_ENUMR(void *adr, SYSTEM_ADRINT *typ, SYSTEM_ADRINT size, SYSTEM_ADRI
     while (n > 0) {
         t = typ;
         off = *t;
-        while (off >= 0) {P(*(SYSTEM_ADRINT*)((char*)adr+off)); t++; off = *t;}
+        while (off >= 0) {P(*(void**)((char*)adr+off)); t++; off = *t;}
         adr = ((char*)adr) + size;
         n--;
     }
 }
 
-extern void Heap_Lock();
-extern void Heap_Unlock();
+extern void Heap_Lock (void);
+extern void Heap_Unlock (void);
 
 
 // Program startup
 
-extern void Heap_InitHeap();
+extern void Heap_InitHeap (void);
 
 void SYSTEM_INIT (void *stktop)
 {
@@ -347,7 +347,7 @@ typedef void (*SystemSignalHandler)(INTEGER); // = Platform_SignalHandler
         return FALSE;
     }
 
-    void EnsureConsoleCtrlHandler() {
+    void EnsureConsoleCtrlHandler (void) {
         if (!ConsoleCtrlHandlerSet) {
         SetConsoleCtrlHandler(SystemConsoleCtrlHandler, TRUE);
             ConsoleCtrlHandlerSet = TRUE;
diff --git a/Mod/Lib/SYSTEM.oh b/Mod/Lib/SYSTEM.oh
index a5223767..7438e247 100644
--- a/Mod/Lib/SYSTEM.oh
+++ b/Mod/Lib/SYSTEM.oh
@@ -432,7 +432,7 @@ extern void       Heap_INCREF();
 // Main module initialization, registration and finalization
 
 extern void SYSTEM_INIT (void *stktop);
-extern void Heap_FINALL();
+extern void Heap_FINALL (void);
 
 #define __INIT(argc, argv)    static void *m; SYSTEM_INIT(stktop)
 #define __REGMAIN(name, enum) m = Heap_REGMOD((CHAR*)name, 32, (void*)enum)
@@ -454,8 +454,8 @@ extern SYSTEM_PTR SYSTEM_NEWARR(SYSTEM_ADRINT*, SYSTEM_ARRLEN, int, int, int, ..
 /* Type handling */
 
 extern void SYSTEM_INHERIT(SYSTEM_ADRINT *t, SYSTEM_ADRINT *t0);
-extern void SYSTEM_ENUMP  (void *adr, SYSTEM_ADRINT n, void (*P)());
-extern void SYSTEM_ENUMR  (void *adr, SYSTEM_ADRINT *typ, SYSTEM_ADRINT size, SYSTEM_ADRINT n, void (*P)());
+extern void SYSTEM_ENUMP  (void *adr, SYSTEM_ADRINT n, void (*P)(void*));
+extern void SYSTEM_ENUMR  (void *adr, SYSTEM_ADRINT *typ, SYSTEM_ADRINT size, SYSTEM_ADRINT n, void (*P)(void*));
 
 #define __TDESC(t__desc, m, n)                                                \
   static struct t__desc {                                                     \