diff --git a/src/assembler/instructions.c b/src/assembler/instructions.c
index 4ba0fc0..f45db15 100644
--- a/src/assembler/instructions.c
+++ b/src/assembler/instructions.c
@@ -176,7 +176,7 @@ static ASMErrorDesc parse_args(
         } else {
             if ((c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') ||
                  c == ' ' || c == '+' || c == '-' || c == '(' || c == ')' ||
-                 c == '$' || c == '_' || c == '.')
+                 c == '$' || c == '_' || c == '.' || c == '\'')
                 i++;
             else
                 return ED_PS_ARG_SYNTAX;
diff --git a/src/assembler/parse_util.c b/src/assembler/parse_util.c
index e5c4c02..269da38 100644
--- a/src/assembler/parse_util.c
+++ b/src/assembler/parse_util.c
@@ -406,7 +406,7 @@ bool argparse_indirect(ASMArgIndirect *result, ASMArgParseInfo ai)
     ASMArgRegister reg;
     ASMArgImmediate imm;
     if (argparse_register(&reg, ai)) {
-        if (reg == REG_BC || reg == REG_DE || reg == REG_HL ||
+        if (reg == REG_BC || reg == REG_DE || reg == REG_HL || reg == REG_SP ||
                              reg == REG_IX || reg == REG_IY) {
             result->type = AT_REGISTER;
             result->addr.reg = reg;