diff --git a/include/cyclone/runtime.h b/include/cyclone/runtime.h
index b206935a..cb0ed6e6 100644
--- a/include/cyclone/runtime.h
+++ b/include/cyclone/runtime.h
@@ -14,7 +14,8 @@
   object l = Cyc_length(data, args); \
   if (num_args > obj_obj2int(l)) { \
     char buf[128]; \
-    snprintf(buf, 127, "Expected %d arguments but received %ld.", num_args, obj_obj2int(l));  \
+    snprintf(buf, 127, "Expected %d arguments to %s but received %ld.", \
+             num_args, fnc_name, obj_obj2int(l));  \
     Cyc_rt_raise_msg(data, buf); \
   } \
 }
diff --git a/runtime.c b/runtime.c
index f9f54eda..c1df6ac7 100644
--- a/runtime.c
+++ b/runtime.c
@@ -2711,7 +2711,7 @@ void _length(void *data, object cont, object args)
 
 void _bytevector_91length(void *data, object cont, object args)
 {
-  Cyc_check_num_args(data, "bytevector_91length", 1, args);
+  Cyc_check_num_args(data, "bytevector-length", 1, args);
   {
     object obj = Cyc_bytevector_length(data, car(args));
     return_closcall1(data, cont, obj);
@@ -2770,7 +2770,7 @@ void _Cyc_91utf8_91_125string(void *data, object cont, object args)
 
 void _vector_91length(void *data, object cont, object args)
 {
-  Cyc_check_num_args(data, "vector_91length", 1, args);
+  Cyc_check_num_args(data, "vector-length", 1, args);
   {
     object obj = Cyc_vector_length(data, car(args));
     return_closcall1(data, cont, obj);