mips

trying to write a method to check if a string is equal to a new line ' '

so i do

is_nl: li $v0, 0

beq $a0, ' ', is_nl

jr $ra

is_nl: li $v0, 1 jr $ra

but when i test it, it doesnot work, this is what my main looks like

.data letter: .asciiz " " .globl main .text main:

la $a0, letter jal is_whitespace move $t1,$v0

li $v0, 10 syscall

if i do lh in the method it will work, but why wont lw work? what is the string is ' q'