diff --git a/docs/index.html b/docs/index.html
index 54f3c81c9..16ba0e21c 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -1853,6 +1853,12 @@
 			<td>Shift-Cmd + n</td>
 		</tr>
 
+		<tr>
+			<td>Toggle TIA HMOVE blanks</td>
+			<td>Alt + m</td>
+			<td>Shift-Cmd + m</td>
+		</tr>
+
 		<tr>
 			<td>Toggle TIA 'Fixed Debug Colors' mode</td>
 			<td>Alt + Comma</td>
diff --git a/src/emucore/Console.cxx b/src/emucore/Console.cxx
index a4b3f8775..385b0210b 100644
--- a/src/emucore/Console.cxx
+++ b/src/emucore/Console.cxx
@@ -794,6 +794,15 @@ void Console::toggleTIABit(TIABit bit, const string& bitname, bool show) const
   myOSystem->frameBuffer().showMessage(message);
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+void Console::toggleHMOVE() const
+{
+  if(myTIA->toggleHMOVEBlank())
+    myOSystem->frameBuffer().showMessage("HMOVE blanking enabled");
+  else
+    myOSystem->frameBuffer().showMessage("HMOVE blanking disabled");
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void Console::enableBits(bool enable) const
 {
diff --git a/src/emucore/Console.hxx b/src/emucore/Console.hxx
index 54fb027b4..4eb131bfc 100644
--- a/src/emucore/Console.hxx
+++ b/src/emucore/Console.hxx
@@ -262,6 +262,7 @@ class Console : public Serializable
     void toggleM1Bit() const { toggleTIABit(M1Bit, "M1"); }
     void toggleBLBit() const { toggleTIABit(BLBit, "BL"); }
     void togglePFBit() const { toggleTIABit(PFBit, "PF"); }
+    void toggleHMOVE() const;
     void enableBits(bool enable) const;
 
     /**
diff --git a/src/emucore/EventHandler.cxx b/src/emucore/EventHandler.cxx
index 05be3622b..da5cade39 100644
--- a/src/emucore/EventHandler.cxx
+++ b/src/emucore/EventHandler.cxx
@@ -392,6 +392,10 @@ void EventHandler::poll(uInt64 time)
                 myOSystem->console().togglePFBit();
                 break;
 
+              case SDLK_m:
+                myOSystem->console().toggleHMOVE();
+                break;
+
               case SDLK_COMMA:
                 myOSystem->console().toggleFixedColors();
                 break;
diff --git a/src/emucore/TIA.cxx b/src/emucore/TIA.cxx
index 016eebc92..0b165d186 100644
--- a/src/emucore/TIA.cxx
+++ b/src/emucore/TIA.cxx
@@ -126,6 +126,7 @@ void TIA::reset()
   // Currently no objects are enabled or selectively disabled
   myEnabledObjects = 0;
   myDisabledObjects = 0;
+  myAllowHMOVEBlanks = true;
 
   // Some default values for the registers
   myColorPtr = myColor;
@@ -509,8 +510,8 @@ bool TIA::load(Serializer& in)
     mySound.load(in);
 
     // Reset TIA bits to be on
-// TODO - should we enable this, or leave it to the user?
-//    enableBits(true);
+    enableBits(true);
+    myAllowHMOVEBlanks = true;
     myColorPtr = myColor;
   }
   catch(const char* msg)
@@ -741,6 +742,13 @@ bool TIA::toggleBit(TIABit b, uInt8 mode)
   return on;
 }
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+bool TIA::toggleHMOVEBlank()
+{
+  myAllowHMOVEBlanks = myAllowHMOVEBlanks ? false : true;
+  return myAllowHMOVEBlanks;
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool TIA::toggleFixedColors(uInt8 mode)
 {
@@ -953,9 +961,10 @@ void TIA::updateFrame(Int32 clock)
         // TODO - 08-27-2009: Simulate the weird effects of Cosmic Ark and
         // Stay Frosty.  The movement itself is well understood, but there
         // also seems to be some widening and blanking occurring as well.
-        // This doesn't properly emulate the effect, but it does give a
-        // fair approximation.  More testing is required to figure out
-        // what's really going on here.
+        // This doesn't properly emulate the effect at a low level; it only
+        // simulates the behaviour as visually seen in the aforementioned
+        // ROMs.  Other ROMs may break this simulation; more testing is
+        // required to figure out what's really going on here.
         if(myHMM0mmr && myPOSM0 % 4 == 3)
         {
           // Stretch this missle so it's 4 pixels wide, with the 3rd pixel
@@ -1026,7 +1035,7 @@ void TIA::updateFrame(Int32 clock)
 
       // TODO - 01-21-99: These should be reset right after the first copy
       // of the player has passed.  However, for now we'll just reset at the
-      // end of the scanline since the other way would be to slow.
+      // end of the scanline since the other way would be too slow.
       mySuppressP0 = mySuppressP1 = 0;
     }
   }
@@ -1838,11 +1847,9 @@ void TIA::poke(uInt16 addr, uInt8 value)
       int hpos = (clock - myClockWhenFrameStarted) % 228 - HBLANK;
       myCurrentHMOVEPos = hpos;
 
-      // Figure out what cycle we're at
-      Int32 x = ((clock - myClockWhenFrameStarted) % 228) / 3;
-
       // See if we need to enable the HMOVE blank bug
-      myHMOVEBlankEnabled = TIATables::HMOVEBlankEnableCycles[x];
+      myHMOVEBlankEnabled = myAllowHMOVEBlanks ? 
+        TIATables::HMOVEBlankEnableCycles[((clock - myClockWhenFrameStarted) % 228) / 3] : false;
 
 #ifdef USE_MMR_LATCHES
       // Do we have to undo some of the already applied cycles from an
diff --git a/src/emucore/TIA.hxx b/src/emucore/TIA.hxx
index 626e8b31e..c34fe3a48 100644
--- a/src/emucore/TIA.hxx
+++ b/src/emucore/TIA.hxx
@@ -265,6 +265,13 @@ class TIA : public Device
     */
     bool toggleBit(TIABit b, uInt8 mode = 2);
 
+    /**
+      Toggle the display of HMOVE blanks.
+
+      @return  Whether the HMOVE blanking was enabled or disabled
+    */
+    bool toggleHMOVEBlank();
+
     /**
       Enables/disable/toggle 'fixed debug colors' mode.
 
@@ -525,6 +532,7 @@ class TIA : public Device
     Int32 myCurrentHMOVEPos;
     Int32 myPreviousHMOVEPos;
     bool myHMOVEBlankEnabled;
+    bool myAllowHMOVEBlanks;
 
     // Indicates if unused TIA pins are floating on a peek
     bool myFloatTIAOutputPins;