diff --git a/src/buildvm_arm.dasc b/src/buildvm_arm.dasc
index c52cfc6c..9d2efa67 100644
--- a/src/buildvm_arm.dasc
+++ b/src/buildvm_arm.dasc
@@ -15,6 +15,70 @@
 |
 |//-----------------------------------------------------------------------
 |
+|// Fixed register assignments for the interpreter.
+|
+|// The following must be C callee-save (but BASE is often refetched).
+|.define BASE,		r4	// Base of current Lua stack frame.
+|.define KBASE,		r5	// Constants of current Lua function.
+|.define PC,		r6	// Next PC.
+|.define DISPATCH,	r7	// Opcode dispatch table.
+|.define LREG,		r8	// Register holding lua_State (also in SAVE_L).
+|.define MASKR8,	r9	// 255*8 constant for fast bytecode decoding.
+|
+|// The following temporaries are not saved across C calls, except for RA/RC.
+|.define RA,		r10	// Callee-save.
+|.define RC,		r11	// Callee-save.
+|.define RB,		r12
+|.define OP,		r12	// Overlaps RB, must not be lr.
+|.define INS,		lr
+|
+|// Calling conventions. Also used as temporaries.
+|.define CARG1,		r0
+|.define CARG2,		r1
+|.define CARG3,		r2
+|.define CARG4,		r3
+|.define CARG12,	r0	// For 1st soft-fp double.
+|.define CARG34,	r2	// For 2nd soft-fp double.
+|
+|.define CRET1,		r0
+|.define CRET2,		r1
+|
+|// Stack layout while in interpreter. Must match with lj_frame.h.
+|.define CFRAME_SPACE,	#28
+|.define SAVE_ERRF,	[sp, #24]
+|.define SAVE_NRES,	[sp, #20]
+|.define SAVE_CFRAME,	[sp, #16]
+|.define SAVE_L,	[sp, #12]
+|.define SAVE_PC,	[sp, #8]
+|.define SAVE_MULTRES,	[sp, #4]
+|.define ARG5,		[sp]
+|
+|.macro saveregs
+|  push {r4, r5, r6, r7, r8, r9, r10, r11, lr}
+|  sub sp, sp, CFRAME_SPACE
+|.endmacro
+|.macro restoreregs_ret
+|  add sp, sp, CFRAME_SPACE
+|  pop {r4, r5, r6, r7, r8, r9, r10, r11, pc}
+|.endmacro
+|
+|// Type definitions. Some of these are only used for documentation.
+|.type L,		lua_State,	LREG
+|.type GL,		global_State
+|.type TVALUE,		TValue
+|.type GCOBJ,		GCobj
+|.type STR,		GCstr
+|.type TAB,		GCtab
+|.type LFUNC,		GCfuncL
+|.type CFUNC,		GCfuncC
+|.type PROTO,		GCproto
+|.type UPVAL,		GCupval
+|.type NODE,		Node
+|.type NARGS8,		int
+|.type TRACE,		GCtrace
+|
+|//-----------------------------------------------------------------------
+|
 |// Trap for not-yet-implemented parts.
 |.macro NYI; ud; .endmacro
 |
diff --git a/src/lj_frame.h b/src/lj_frame.h
index 21074724..c123353e 100644
--- a/src/lj_frame.h
+++ b/src/lj_frame.h
@@ -91,13 +91,12 @@ enum {
 #define CFRAME_SHIFT_MULTRES	0
 #endif
 #elif LJ_TARGET_ARM
-/* NYI: Dummy definitions for now. */
-#define CFRAME_OFS_ERRF		28
-#define CFRAME_OFS_NRES		24
-#define CFRAME_OFS_PREV		20
-#define CFRAME_OFS_L		16
-#define CFRAME_OFS_PC		12
-#define CFRAME_OFS_MULTRES	8
+#define CFRAME_OFS_ERRF		24
+#define CFRAME_OFS_NRES		20
+#define CFRAME_OFS_PREV		16
+#define CFRAME_OFS_L		12
+#define CFRAME_OFS_PC		8
+#define CFRAME_OFS_MULTRES	4
 #define CFRAME_SIZE		64
 #define CFRAME_SIZE_JIT		CFRAME_SIZE
 #define CFRAME_SHIFT_MULTRES	3