diff --git a/src/crab/cpu.cr b/src/crab/cpu.cr
index 6c2d78f..4655e34 100644
--- a/src/crab/cpu.cr
+++ b/src/crab/cpu.cr
@@ -136,8 +136,10 @@ class CPU
       else
         arm_execute instr
       end
+      @gba.scheduler.tick 1
+    else
+      @gba.scheduler.fast_forward
     end
-    @gba.tick 1
   end
 
   def check_cond(cond : Word) : Bool
diff --git a/src/crab/gba.cr b/src/crab/gba.cr
index d50d69a..4ea8076 100644
--- a/src/crab/gba.cr
+++ b/src/crab/gba.cr
@@ -83,8 +83,4 @@ class GBA
       cpu.tick
     end
   end
-
-  def tick(cycles : Int) : Nil
-    scheduler.tick cycles
-  end
 end
diff --git a/src/crab/mmio.cr b/src/crab/mmio.cr
index 4705503..075257c 100644
--- a/src/crab/mmio.cr
+++ b/src/crab/mmio.cr
@@ -67,7 +67,11 @@ class MMIO
       mask = 0xFF00_u16 >> shift
       @waitcnt.value = (@waitcnt.value & mask) | value.to_u16 << shift
     elsif io_addr == 0x301
-      @gba.cpu.halted = bit?(value, 7)
+      if bit?(value, 7)
+        abort "Stopping not supported"
+      else
+        @gba.cpu.halted = true
+      end
     elsif not_used? io_addr
     else
       puts "Unmapped MMIO write ~ addr:#{hex_str index.to_u32}, val:#{hex_str value}".colorize(:yellow)
diff --git a/src/crab/scheduler.cr b/src/crab/scheduler.cr
index 9b1d0e0..648918e 100644
--- a/src/crab/scheduler.cr
+++ b/src/crab/scheduler.cr
@@ -63,4 +63,9 @@ class Scheduler
       end
     end
   end
+
+  def fast_forward : Nil
+    @cycles = @next_event
+    call_current
+  end
 end