diff --git a/src/grib_accessor_class_smart_table.c b/src/grib_accessor_class_smart_table.c
index 70fa29a6e..5d2318ad7 100644
--- a/src/grib_accessor_class_smart_table.c
+++ b/src/grib_accessor_class_smart_table.c
@@ -571,6 +571,13 @@ static int unpack_long(grib_accessor* a, long* val, size_t* len)
     if (err)
         return 0;
 
+    if (*len < self->tableCodesSize) {
+        grib_context_log(a->context, GRIB_LOG_ERROR,
+                         " wrong size (%ld) for %s it contains %d values ", *len, a->name, self->tableCodesSize);
+        *len = 0;
+        return GRIB_ARRAY_TOO_SMALL;
+    }
+
     for (i = 0; i < self->tableCodesSize; i++)
         val[i] = self->tableCodes[i];