diff --git a/src/sim65/6502.c b/src/sim65/6502.c
index 6c23b0dfc..9d2c93da8 100644
--- a/src/sim65/6502.c
+++ b/src/sim65/6502.c
@@ -64,18 +64,12 @@ static CPURegs Regs;
 /* Cycles for the current insn */
 static unsigned Cycles;
 
-/* Total number of CPU cycles exec'd */
-static unsigned long TotalCycles;
-
 /* NMI request active */
 static unsigned HaveNMIRequest;
 
 /* IRQ request active */
 static unsigned HaveIRQRequest;
 
-/* flag to print cycles at program termination */
-int PrintCycles;
-
 
 /*****************************************************************************/
 /*                        Helper functions and macros                        */
@@ -3277,18 +3271,6 @@ unsigned ExecuteInsn (void)
         Handlers[CPU][OPC] ();
     }
 
-    /* Count cycles */
-    TotalCycles += Cycles;
-
     /* Return the number of clock cycles needed by this insn */
     return Cycles;
 }
-
-
-
-unsigned long GetCycles (void)
-/* Return the total number of cycles executed */
-{
-    /* Return the total number of cycles */
-    return TotalCycles;
-}
diff --git a/src/sim65/6502.h b/src/sim65/6502.h
index f8e894567..39b995793 100644
--- a/src/sim65/6502.h
+++ b/src/sim65/6502.h
@@ -96,12 +96,6 @@ unsigned ExecuteInsn (void);
 ** executed instruction.
 */
 
-unsigned long GetCycles (void);
-/* Return the total number of clock cycles executed */
-
-extern int PrintCycles;
-/* flag to print cycles at program termination */
-
 
 /* End of 6502.h */
 
diff --git a/src/sim65/error.c b/src/sim65/error.c
index 441b07d2a..fc24ca006 100644
--- a/src/sim65/error.c
+++ b/src/sim65/error.c
@@ -41,6 +41,20 @@
 
 
 
+/*****************************************************************************/
+/*                                   Data                                    */
+/*****************************************************************************/
+
+
+
+/* flag to print cycles at program termination */
+int PrintCycles = 0;
+
+/* cycles are counted by main.c */
+extern unsigned long long TotalCycles;
+
+
+
 /*****************************************************************************/
 /*                                   Code                                    */
 /*****************************************************************************/
@@ -99,3 +113,14 @@ void Internal (const char* Format, ...)
     va_end (ap);
     exit (SIM65_ERROR);
 }
+
+
+
+void SimExit (int Code)
+/* Exit the simulation with an exit code */
+{
+    if (PrintCycles) {
+        fprintf (stdout, "%llu cycles\n", TotalCycles);
+    }
+    exit (Code);
+}
diff --git a/src/sim65/error.h b/src/sim65/error.h
index ea54fa048..a016881c6 100644
--- a/src/sim65/error.h
+++ b/src/sim65/error.h
@@ -55,6 +55,9 @@
 #define SIM65_ERROR_TIMEOUT 0x7E
 /* An error result for max CPU instructions exceeded. */
 
+extern int PrintCycles;
+/* flag to print cycles at program termination */
+
 
 
 /*****************************************************************************/
@@ -75,6 +78,9 @@ void ErrorCode (int Code, const char* Format, ...) attribute((noreturn, format(p
 void Internal (const char* Format, ...) attribute((noreturn, format(printf,1,2)));
 /* Print an internal error message and die */
 
+void SimExit (int Code);
+/* Exit the simulation with an exit code */
+
 
 
 /* End of error.h */
diff --git a/src/sim65/main.c b/src/sim65/main.c
index d92d52ef6..f5ace1909 100644
--- a/src/sim65/main.c
+++ b/src/sim65/main.c
@@ -36,7 +36,6 @@
 #include <string.h>
 #include <stdlib.h>
 #include <errno.h>
-#include <limits.h>
 
 /* common */
 #include "abend.h"
@@ -61,14 +60,14 @@
 /* Name of program file */
 const char* ProgramFile;
 
-/* exit simulator after MaxCycles Cycles */
-unsigned long MaxCycles;
+/* count of total cycles executed */
+unsigned long long TotalCycles = 0;
 
-/* maximum number of cycles that can be tested,
-** requires overhead for longest possible instruction,
-** which should be 7, using 16 for safety.
-*/
-#define MAXCYCLES_LIMIT (ULONG_MAX-16)
+/* exit simulator after MaxCycles Cccles */
+unsigned long long MaxCycles = 0;
+
+/* countdown from MaxCycles */
+unsigned long long RemainCycles;
 
 /* Header signature 'sim65' */
 static const unsigned char HeaderSignature[] = {
@@ -145,11 +144,7 @@ static void OptQuitXIns (const char* Opt attribute ((unused)),
                         const char* Arg attribute ((unused)))
 /* quit after MaxCycles cycles */
 {
-    MaxCycles = strtoul(Arg, NULL, 0);
-    /* Guard against overflow. */
-    if (MaxCycles >= MAXCYCLES_LIMIT) {
-        Error("'-x parameter out of range. Max: %lu",MAXCYCLES_LIMIT);
-    }
+    MaxCycles = strtoull(Arg, NULL, 0);
 }
 
 static unsigned char ReadProgramFile (void)
@@ -247,6 +242,7 @@ int main (int argc, char* argv[])
 
     unsigned I;
     unsigned char SPAddr;
+    unsigned int Cycles;
 
     /* Initialize the cmdline module */
     InitCmdLine (&argc, &argv, "sim65");
@@ -309,18 +305,24 @@ int main (int argc, char* argv[])
     MemInit ();
 
     SPAddr = ReadProgramFile ();
-
     ParaVirtInit (I, SPAddr);
 
     Reset ();
 
+    RemainCycles = MaxCycles;
     while (1) {
-        ExecuteInsn ();
-        if (MaxCycles && (GetCycles () >= MaxCycles)) {
-            ErrorCode (SIM65_ERROR_TIMEOUT, "Maximum number of cycles reached.");
+        Cycles = ExecuteInsn ();
+        TotalCycles += Cycles;
+        if (MaxCycles) {
+            if (Cycles > RemainCycles) {
+                ErrorCode (SIM65_ERROR_TIMEOUT, "Maximum number of cycles (%llu) reached.", MaxCycles);
+            }
+            RemainCycles -= Cycles;
         }
     }
 
-    /* Return an apropriate exit code */
-    return EXIT_SUCCESS;
+    /* Unreachable. sim65 program must exit through paravirtual PVExit
+    ** or timeout from MaxCycles producing an error.
+    */
+    return SIM65_ERROR;
 }
diff --git a/src/sim65/paravirt.c b/src/sim65/paravirt.c
index 0b16f89e9..af162acfa 100644
--- a/src/sim65/paravirt.c
+++ b/src/sim65/paravirt.c
@@ -124,11 +124,7 @@ static unsigned PopParam (unsigned char Incr)
 static void PVExit (CPURegs* Regs)
 {
     Print (stderr, 1, "PVExit ($%02X)\n", Regs->AC);
-    if (PrintCycles) {
-        Print (stdout, 0, "%lu cycles\n", GetCycles ());
-    }
-
-    exit (Regs->AC);
+    SimExit (Regs->AC);
 }