diff --git a/src/emu/i8088.rs b/src/emu/i8088.rs
index 071069b..5ffeffb 100644
--- a/src/emu/i8088.rs
+++ b/src/emu/i8088.rs
@@ -179,27 +179,27 @@ macro_rules! step {
   };
 
   (@form=byte0 $cookie:tt, $cpu:expr, $bus:expr, $prefix:tt, $modrm:tt) => {
-    step!(@form $cookie, form=(u8));
+    step!(@form $cookie, form=(u8))
   };
 
   (@form=byte1 $cookie:tt, $cpu:expr, $bus:expr, $prefix:tt, $modrm:tt) => {
-    step!(@form $cookie, form=(u8, _));
+    step!(@form $cookie, form=(u8, _))
   };
 
   (@form=byte3 $cookie:tt, $cpu:expr, $bus:expr, $prefix:tt, $modrm:tt) => {
-    step!(@form $cookie, form=(u8, _, _, _));
+    step!(@form $cookie, form=(u8, _, _, _))
   };
 
   (@form=word0 $cookie:tt, $cpu:expr, $bus:expr, $prefix:tt, $modrm:tt) => {
-    step!(@form $cookie, form=(u16));
+    step!(@form $cookie, form=(u16))
   };
 
   (@form=word1 $cookie:tt, $cpu:expr, $bus:expr, $prefix:tt, $modrm:tt) => {
-    step!(@form $cookie, form=(u16, _));
+    step!(@form $cookie, form=(u16, _))
   };
 
   (@form=word3 $cookie:tt, $cpu:expr, $bus:expr, $prefix:tt, $modrm:tt) => {
-    step!(@form $cookie, form=(u16, _, _, _));
+    step!(@form $cookie, form=(u16, _, _, _))
   };
 
   (@mem $cookie:tt, $cpu:expr, $bus:expr, $prefix:tt, $modrm:tt) => {
@@ -253,35 +253,45 @@ macro_rules! step {
     continue $prefix_loop;
   };
 
-  (@r16 $cookie:tt, $cpu:expr, $bus:expr, $prefix:tt, ($modrm_val:ident, $modrm:tt, $modrm16:tt, $modrm8:tt)) => {
+  (@r16 $cookie:tt, $cpu:expr, $bus:expr, $prefix:tt, ($modrm_val:ident, $($modrm_rest:tt),*)) => { {
     // TODO: Should these also be passed into the macro like the modrm specs?
-    match $modrm_val >> 3 & 0x7 {
-      0 => step!(@arg $cookie, Reg { reg: &$cpu.a } ),
-      1 => step!(@arg $cookie, Reg { reg: &$cpu.c } ),
-      2 => step!(@arg $cookie, Reg { reg: &$cpu.d } ),
-      3 => step!(@arg $cookie, Reg { reg: &$cpu.b } ),
-      4 => step!(@arg $cookie, Reg { reg: &$cpu.sp } ),
-      5 => step!(@arg $cookie, Reg { reg: &$cpu.bp } ),
-      6 => step!(@arg $cookie, Reg { reg: &$cpu.si } ),
-      7 => step!(@arg $cookie, Reg { reg: &$cpu.di } ),
+    let reg = match $modrm_val >> 3 & 0x7 {
+      0 => Reg { reg: &$cpu.a },
+      1 => Reg { reg: &$cpu.c },
+      2 => Reg { reg: &$cpu.d },
+      3 => Reg { reg: &$cpu.b },
+      4 => Reg { reg: &$cpu.sp },
+      5 => Reg { reg: &$cpu.bp },
+      6 => Reg { reg: &$cpu.si },
+      7 => Reg { reg: &$cpu.di },
       _ => unreachable!()
     };
-  };
+    step!(@arg $cookie, reg)
+  } };
 
-  (@r8 $cookie:tt, $cpu:expr, $bus:expr, $prefix:tt, ($modrm_val:ident, $modrm:tt, $modrm16:tt, $modrm8:tt)) => {
+  (@r8 $cookie:tt, $cpu:expr, $bus:expr, $prefix:tt, ($modrm_val:ident, $($modrm_rest:tt),*)) => { {
+    let modrm_shift = $modrm_val >> 3;
     // TODO: Should these also be passed into the macro like the modrm specs?
-    match $modrm_val >> 3 & 0x7 {
-      0 => step!(@arg $cookie, RegLo { reg: &$cpu.a } ),
-      1 => step!(@arg $cookie, RegLo { reg: &$cpu.c } ),
-      2 => step!(@arg $cookie, RegLo { reg: &$cpu.d } ),
-      3 => step!(@arg $cookie, RegLo { reg: &$cpu.b } ),
-      4 => step!(@arg $cookie, RegHi { reg: &$cpu.a } ),
-      5 => step!(@arg $cookie, RegHi { reg: &$cpu.c } ),
-      6 => step!(@arg $cookie, RegHi { reg: &$cpu.d } ),
-      7 => step!(@arg $cookie, RegHi { reg: &$cpu.b } ),
-      _ => unreachable!()
-    };
-  };
+    if modrm_shift & 0x4 == 0 {
+      let reg = match modrm_shift & 0x3 {
+        0 => RegLo { reg: &$cpu.a },
+        1 => RegLo { reg: &$cpu.c },
+        2 => RegLo { reg: &$cpu.d },
+        3 => RegLo { reg: &$cpu.b },
+        _ => unreachable!()
+      };
+      step!(@arg $cookie, reg)
+    } else {
+      let reg = match modrm_shift & 0x3 {
+        0 => RegHi { reg: &$cpu.a },
+        1 => RegHi { reg: &$cpu.c },
+        2 => RegHi { reg: &$cpu.d },
+        3 => RegHi { reg: &$cpu.b },
+        _ => unreachable!()
+      };
+      step!(@arg $cookie, reg)
+    }
+  } };
 
   (@reg=$reg:ident $cookie:tt, $cpu:expr, $bus:expr, $prefix:tt, $modrm:tt) => {
     step!(@arg $cookie, Reg { reg: &$cpu.$reg });