diff --git a/SheepShaver/src/Unix/main_unix.cpp b/SheepShaver/src/Unix/main_unix.cpp
index d5580a51..34c104cc 100755
--- a/SheepShaver/src/Unix/main_unix.cpp
+++ b/SheepShaver/src/Unix/main_unix.cpp
@@ -401,6 +401,8 @@ static void get_system_info(void)
 
 #if EMULATED_PPC
 	PVR = 0x000c0000;			// Default: 7400 (with AltiVec)
+	int pref_cpu_clock = PrefsFindInt32("cpuclock");
+	if (pref_cpu_clock) CPUClockSpeed = 1000000 * pref_cpu_clock;
 #elif defined(__APPLE__) && defined(__MACH__)
 	proc_file = popen("ioreg -c IOPlatformDevice", "r");
 	if (proc_file) {
diff --git a/SheepShaver/src/Windows/main_windows.cpp b/SheepShaver/src/Windows/main_windows.cpp
index 22cafb45..0683c471 100755
--- a/SheepShaver/src/Windows/main_windows.cpp
+++ b/SheepShaver/src/Windows/main_windows.cpp
@@ -249,6 +249,10 @@ int main(int argc, char **argv)
 	TimebaseSpeed =  25000000;	// Default:  25MHz
 	PVR = 0x000c0000;			// Default: 7400 (with AltiVec)
 	D(bug("PVR: %08x (assumed)\n", PVR));
+	{
+		int pref_cpu_clock = PrefsFindInt32("cpuclock");
+		if (pref_cpu_clock) CPUClockSpeed = 1000000 * pref_cpu_clock;
+	}
 
 	// Init system routines
 	SysInit();
diff --git a/SheepShaver/src/prefs_items.cpp b/SheepShaver/src/prefs_items.cpp
index b0a9f919..5a7f7761 100644
--- a/SheepShaver/src/prefs_items.cpp
+++ b/SheepShaver/src/prefs_items.cpp
@@ -62,6 +62,7 @@ prefs_desc common_prefs_items[] = {
 	{"hotkey", TYPE_INT32, false,       "hotkey modifier"},
 	{"scale_nearest",TYPE_BOOLEAN,false,"nearest neighbor scaling"},
 	{"scale_integer",TYPE_BOOLEAN,false,"integer scaling"},
+	{"cpuclock", TYPE_INT32, 0,			"CPU clock [MHz] of system info"},
 	{NULL, TYPE_END, false, NULL} // End of list
 };