test$ cat test.asm

fmulp st1, st0
fmulp st1
test$ ~/proj/nasm-03490692b0082fe16a1936a5774f4326a55075e6/nasm test.asm -l /dev/stderr
     1
     2 00000000 DEC9                    fmulp st1, st0
     3 00000002 DEC9                    fmulp st1
test$ ~/proj/nasm-755593b12844a3189dcab7faf3e9158da0877021/nasm test.asm -l /dev/stderr
     1
test.asm:2: error: invalid combination of opcode and operands
     2                                  fmulp st1, st0
     2          ******************       error: invalid combination of opcode and operands
     3 00000000 DEC9                    fmulp st1
test$ ~/proj/nasm-ac0429fb74e544c78c0e1556483b0196462dad18/nasm test.asm -l /dev/stderr
     1
     2 00000000 DEC9                    fmulp st1, st0
     3 00000002 DEC9                    fmulp st1
test$