diff --git a/src/parser/grammar.h b/src/parser/grammar.h
index 80961f1..3faf39d 100644
--- a/src/parser/grammar.h
+++ b/src/parser/grammar.h
@@ -11,7 +11,7 @@
     peek_token(ctx);                                                           \
     if (token == NULL)                                                         \
     {                                                                          \
-        puts("Internal error: cannot get the following token");                \
+        perror("Internal error: cannot get the following token");                \
         return NULL;                                                           \
     }
 
@@ -19,7 +19,7 @@
     pop_token(ctx);                                                            \
     if (token == NULL)                                                         \
     {                                                                          \
-        puts("Internal error: cannot get the following token");                \
+        perror("Internal error: cannot get the following token");                \
         return NULL;                                                           \
     }