diff --git a/src/main/scala/millfork/parser/Preprocessor.scala b/src/main/scala/millfork/parser/Preprocessor.scala
index 4d9d16db..c998ae34 100644
--- a/src/main/scala/millfork/parser/Preprocessor.scala
+++ b/src/main/scala/millfork/parser/Preprocessor.scala
@@ -121,7 +121,7 @@ object Preprocessor {
               log.error("Invalid preprocessor directive: #" + keyword, pos)
 
           }
-        case _ => if (enabled) resulting = line
+        case _ => if (enabled) resulting = line.replace("\t", "    ")
       }
       result += resulting
     }