diff --git a/src/emucore/CartDetector.cxx b/src/emucore/CartDetector.cxx
index d6b319ee3..72e3d7d98 100644
--- a/src/emucore/CartDetector.cxx
+++ b/src/emucore/CartDetector.cxx
@@ -946,12 +946,12 @@ bool CartDetector::isProbablyFA2(const ByteBuffer& image, size_t)
 bool CartDetector::isProbablyFC(const ByteBuffer& image, size_t size)
 {
   // FC bankswitching uses consecutive writes to 3 hotspots
-  uInt8 signature[2][6] = {
+  uInt8 signature[3][6] = {
     { 0x8d, 0xf8, 0x1f, 0x4a, 0x4a, 0x8d }, // STA $1FF8, LSR, LSR, STA... Power Play Arcade Menus, 3-D Ghost Attack
     { 0x8d, 0xf8, 0xff, 0x8d, 0xfc, 0xff }, // STA $FFF8, STA $FFFC        Surf's Up (4K)
-    //{ 0x8c, 0xf9, 0xff, 0xad, 0xfc, 0xff }  // STY $FFF9, LDA $FFFC        3-D Havoc (patched for F8, ignore!)
+    { 0x8c, 0xf9, 0xff, 0xad, 0xfc, 0xff }  // STY $FFF9, LDA $FFFC        3-D Havoc
   };
-  for (uInt32 i = 0; i < 2; ++i)
+  for (uInt32 i = 0; i < 3; ++i)
     if (searchForBytes(image.get(), size, signature[i], 6, 1))
       return true;
 
diff --git a/src/emucore/CartFC.cxx b/src/emucore/CartFC.cxx
index a5f3e74a0..75082ff36 100644
--- a/src/emucore/CartFC.cxx
+++ b/src/emucore/CartFC.cxx
@@ -86,8 +86,14 @@ bool CartridgeFC::poke(uInt16 address, uInt8 value)
 
     case 0x0FF9:
       // Set the high bits of target 4k bank
-      myTargetBank += value << 2;
-      myTargetBank %= bankCount();
+      if (value << 2 < bankCount())
+      {
+        myTargetBank += value << 2;
+        myTargetBank %= bankCount();
+      }
+      else
+        // special handling when both values are identical (e.g. 4/4 or 5/5)
+        myTargetBank = value % bankCount();
       break;
 
     case 0x0FFC: