diff --git a/src/accessor/grib_accessor_class_ascii.cc b/src/accessor/grib_accessor_class_ascii.cc
index e6d9a3436..d3c9bea69 100644
--- a/src/accessor/grib_accessor_class_ascii.cc
+++ b/src/accessor/grib_accessor_class_ascii.cc
@@ -66,16 +66,16 @@ int grib_accessor_ascii_t::pack_string(const char* val, size_t* len)
 {
     grib_handle* hand = grib_handle_of_accessor(this);
     const size_t alen = length_;
-    if (len[0] > (alen + 1)) {
+    if (*len > (alen + 1)) {
         grib_context_log(context_, GRIB_LOG_ERROR,
-                         "pack_string: Wrong size (%zu) for %s, it contains %ld values",
-                         len[0], name_, length_ + 1);
-        len[0] = 0;
+                        "%s: Buffer too small for %s. It is %zu bytes long (input string len=%zu)",
+                        class_name_, name_, alen, *len);
+        *len = alen;
         return GRIB_BUFFER_TOO_SMALL;
     }
 
     for (size_t i = 0; i < alen; i++) {
-        if (i < len[0])
+        if (i < *len)
             hand->buffer->data[offset_ + i] = val[i];
         else
             hand->buffer->data[offset_ + i] = 0;