diff --git a/src/parser.c b/src/parser.c
index 03db487..2985b4c 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -104,8 +104,10 @@ void classifyAlias(char *opcode, a64inst_instruction *instr, char *tokens[], int
         char *opcode = ALIAS_TARGET_OPCODES[aliasIndex];
 
         // To correctly encode the zero register, which is either w31 or x31.
+        char *start_zeroReg = tokens[1];
+        while (isspace(*start_zeroReg)) start_zeroReg++;
         char *zeroReg = malloc(5 * sizeof(char));
-        *zeroReg = *tokens[1];
+        *zeroReg = *start_zeroReg;
         strcat(zeroReg, "31");
 
         switch(aliasIndex) {