diff --git a/apps/zasm/README.md b/apps/zasm/README.md
index 89b4d30..644a667 100644
--- a/apps/zasm/README.md
+++ b/apps/zasm/README.md
@@ -191,4 +191,10 @@ the instruction after the "foo" label would be "rjmp foo+1". In zasm, it's
 "rjmp foo+2". If your expression results in an odd number, the low bit of your
 number will be ignored.
 
+Limitations:
+
+* `CALL` and `JMP` only support 16-bit numbers, not 22-bit ones.
+* `BRLO` and `BRSH` are not there. Use `BRCS` and `BRCC` instead.
+* No `high()` and `low()`. Use `&0xff` and `}8`.
+
 [libz80]: https://github.com/ggambetta/libz80
diff --git a/apps/zasm/avr.asm b/apps/zasm/avr.asm
index 0ad0808..67ef31f 100644
--- a/apps/zasm/avr.asm
+++ b/apps/zasm/avr.asm
@@ -94,9 +94,10 @@ instrNames:
 .db "SLEEP", 0
 .db "SUB", 0
 .db "SWAP", 0
+.db "TST", 0
 .db "WDR", 0
 .db "XCH", 0
-.equ	I_ANDI	81
+.equ	I_ANDI	82
 .db "ANDI", 0
 .db "CBR", 0
 .db "CPI", 0
@@ -105,10 +106,10 @@ instrNames:
 .db "SBCI", 0
 .db "SBR", 0
 .db "SUBI", 0
-.equ	I_RCALL	89
+.equ	I_RCALL	90
 .db "RCALL", 0
 .db "RJMP", 0
-.equ	I_CBI	91
+.equ	I_CBI	92
 .db "CBI", 0
 .db "SBI", 0
 .db "SBIC", 0
@@ -117,7 +118,7 @@ instrNames:
 ; ZASM limitation: CALL and JMP constants are 22-bit. In ZASM, we limit
 ; ourselves to 16-bit. Supporting 22-bit would incur a prohibitive complexity
 ; cost. As they say, 64K words ought to be enough for anybody.
-.equ	I_CALL	95
+.equ	I_CALL	96
 .db "CALL", 0
 .db "JMP", 0
 .db 0xff
@@ -209,6 +210,7 @@ instrTbl:
 .db 0x00, 0b10010101, 0b10001000	; SLEEP
 .db 0x02, 0b00011000, 0x00		; SUB Rd, Rr
 .db 0x01, 0b10010100, 0b00000010	; SWAP Rd
+.db 0x41, 0b00100000, 0x00		; TST Rd (Bit 6)
 .db 0x00, 0b10010101, 0b10101000	; WDR
 .db 0x01, 0b10010010, 0b00000100	; XCH Rd
 ; Rd(4) + K(8): XXXXKKKK ddddKKKK
diff --git a/tools/tests/avra/test1.asm b/tools/tests/avra/test1.asm
index f7753b7..025ec6c 100644
--- a/tools/tests/avra/test1.asm
+++ b/tools/tests/avra/test1.asm
@@ -23,3 +23,4 @@ call	foo
 jmp	bar
 mov	r6, r30
 lsl	r3
+tst	r12
diff --git a/tools/tests/avra/test1.expected b/tools/tests/avra/test1.expected
index 9446321..06305e7 100644
Binary files a/tools/tests/avra/test1.expected and b/tools/tests/avra/test1.expected differ