diff --git a/source/mach.c b/source/mach.c
index 2336cf30..f180843f 100644
--- a/source/mach.c
+++ b/source/mach.c
@@ -608,6 +608,11 @@ static int mach_compile_expr(MachCompState *cs, cJSON *node, int dest) {
 
       int ki = mach_cpool_add_str(cs, prop_name);
 
+      /* If ki overflows 8-bit C field, load key into R(base+1) register */
+      if (ki >= 0xFF) {
+        mach_emit(cs, MACH_ABx(MACH_LOADK, base + 1, ki));
+      }
+
       /* Compile args into R(base+2)..R(base+1+nargs) */
       for (int i = 0; i < nargs; i++) {
         int arg_reg = mach_reserve_reg(cs);
@@ -617,7 +622,7 @@ static int mach_compile_expr(MachCompState *cs, cJSON *node, int dest) {
           mach_emit(cs, MACH_ABC(MACH_MOVE, arg_reg, r, 0));
       }
 
-      mach_emit(cs, MACH_ABC(MACH_CALLMETHOD, base, nargs, ki));
+      mach_emit(cs, MACH_ABC(MACH_CALLMETHOD, base, nargs, ki >= 0xFF ? 0xFF : ki));
       mach_free_reg_to(cs, save_freereg);
       if (dest >= 0 && dest != base)
         mach_emit(cs, MACH_ABC(MACH_MOVE, dest, base, 0));
@@ -887,13 +892,25 @@ static int mach_compile_expr(MachCompState *cs, cJSON *node, int dest) {
         if (cs->freereg <= obj_r) cs->freereg = obj_r + 1;
         int ki = mach_cpool_add_str(cs, prop_name);
         int val_r = mach_reserve_reg(cs);
-        mach_emit(cs, MACH_ABC(MACH_GETFIELD, val_r, obj_r, ki));
+        if (ki < 256) {
+          mach_emit(cs, MACH_ABC(MACH_GETFIELD, val_r, obj_r, ki));
+        } else {
+          int kr = mach_reserve_reg(cs);
+          mach_emit(cs, MACH_ABx(MACH_LOADK, kr, ki));
+          mach_emit(cs, MACH_ABC(MACH_GETINDEX, val_r, obj_r, kr));
+        }
         if (is_postfix)
           mach_emit(cs, MACH_ABC(MACH_MOVE, dest, val_r, 0));
         mach_emit(cs, MACH_ABC(inc_op, val_r, val_r, 0));
         if (!is_postfix)
           mach_emit(cs, MACH_ABC(MACH_MOVE, dest, val_r, 0));
-        mach_emit(cs, MACH_ABC(MACH_SETFIELD, obj_r, ki, val_r));
+        if (ki < 256) {
+          mach_emit(cs, MACH_ABC(MACH_SETFIELD, obj_r, ki, val_r));
+        } else {
+          int kr = mach_reserve_reg(cs);
+          mach_emit(cs, MACH_ABx(MACH_LOADK, kr, ki));
+          mach_emit(cs, MACH_ABC(MACH_SETINDEX, obj_r, kr, val_r));
+        }
         mach_free_reg_to(cs, save);
         return dest;
       }
@@ -1063,7 +1080,13 @@ static int mach_compile_expr(MachCompState *cs, cJSON *node, int dest) {
       int val_r = mach_compile_expr(cs, right, dest);
       if (prop_name) {
         int ki = mach_cpool_add_str(cs, prop_name);
-        mach_emit(cs, MACH_ABC(MACH_SETFIELD, obj_r, ki, val_r));
+        if (ki < 256) {
+          mach_emit(cs, MACH_ABC(MACH_SETFIELD, obj_r, ki, val_r));
+        } else {
+          int kr = mach_reserve_reg(cs);
+          mach_emit(cs, MACH_ABx(MACH_LOADK, kr, ki));
+          mach_emit(cs, MACH_ABC(MACH_SETINDEX, obj_r, kr, val_r));
+        }
       }
       mach_free_reg_to(cs, save);
       return val_r;
@@ -1111,7 +1134,13 @@ static int mach_compile_expr(MachCompState *cs, cJSON *node, int dest) {
     int obj_r = mach_compile_expr(cs, obj_expr, -1);
     if (prop_name) {
       int ki = mach_cpool_add_str(cs, prop_name);
-      mach_emit(cs, MACH_ABC(MACH_GETFIELD, dest, obj_r, ki));
+      if (ki < 256) {
+        mach_emit(cs, MACH_ABC(MACH_GETFIELD, dest, obj_r, ki));
+      } else {
+        int kr = mach_reserve_reg(cs);
+        mach_emit(cs, MACH_ABx(MACH_LOADK, kr, ki));
+        mach_emit(cs, MACH_ABC(MACH_GETINDEX, dest, obj_r, kr));
+      }
     }
     mach_free_reg_to(cs, save);
     return dest;
@@ -1155,7 +1184,13 @@ static int mach_compile_expr(MachCompState *cs, cJSON *node, int dest) {
           int save = cs->freereg;
           int vr = mach_compile_expr(cs, val_node, -1);
           int ki = mach_cpool_add_str(cs, key);
-          mach_emit(cs, MACH_ABC(MACH_SETFIELD, dest, ki, vr));
+          if (ki < 256) {
+            mach_emit(cs, MACH_ABC(MACH_SETFIELD, dest, ki, vr));
+          } else {
+            int kr = mach_reserve_reg(cs);
+            mach_emit(cs, MACH_ABx(MACH_LOADK, kr, ki));
+            mach_emit(cs, MACH_ABC(MACH_SETINDEX, dest, kr, vr));
+          }
           mach_free_reg_to(cs, save);
         }
       }