diff --git a/src/base/trie.hh b/src/base/trie.hh
index a75e9e7353..71a14c55cb 100644
--- a/src/base/trie.hh
+++ b/src/base/trie.hh
@@ -31,16 +31,27 @@
 
 #include <cassert>
 #include <iostream>
+#include <type_traits>
 
 #include "base/cprintf.hh"
 #include "base/logging.hh"
 #include "base/types.hh"
 
-// Key has to be an integral type.
+/**
+ * A trie is a tree-based data structure used for data retrieval. It uses
+ * bits masked from the msb of the key to to determine a value's location,
+ * so its lookups have their worst case time dictated by the key's size.
+ *
+ * @tparam Key Type of the key of the tree nodes. Must be an integral type.
+ * @tparam Value Type of the values associated to the keys.
+ */
 template <class Key, class Value>
 class Trie
 {
   protected:
+    static_assert(std::is_integral<Key>::value,
+        "Key has to be an integral type");
+
     struct Node
     {
         Key key;