1 files changed, 1 insertions, 1 deletions
diff --git a/parse.y b/parse.y
index a2109cec25..046ca4581a 100644
--- a/parse.y
+++ b/parse.y
@@ -4192,7 +4192,7 @@ f_block_arg	: blkarg_mark tIDENTIFIER
 			    yyerror("block argument must be local variable");
 			else if (!dyna_in_block() && local_id($2))
 			    yyerror("duplicated block argument name");
-			$$ = NEW_BLOCK_ARG($2);
+			$$ = dyna_in_block() ? assignable($2, 0) : NEW_BLOCK_ARG($2);
 		    /*%
 			$$ = $2;
 		    %*/