diff --git a/include/fractal.hpp b/include/fractal.hpp
index ff295af..dccee7e 100644
--- a/include/fractal.hpp
+++ b/include/fractal.hpp
@@ -101,7 +101,12 @@ public:
 	 *
 	 * @ret @c true if the number of tokens in the ruleset equals @c g_max_tokens, @c false otherwise
 	 */
-	bool tokens_full() const;
+	bool tokens_full() const {
+		return m_tokens.full();
+	}
+	bool valid_token(token_id_t tok) const {
+		return tok < m_tokens.size();
+	}
 
 	/**
 	 * @brief Add new token variable that can be used in this ruleset
@@ -120,7 +125,9 @@ public:
 	 *
 	 * @ret @c true if the number of group characteristics in the ruleset equals @c g_max_cgroups, @c false otherwise
 	 */
-	bool group_characteristics_full() const;
+	bool group_characteristics_full() const {
+		return m_group_characteristics.full();
+	}
 
 	/**
 	 * @brief Add new group characteristic
diff --git a/src/fractal.cpp b/src/fractal.cpp
index 8f21041..20c0731 100644
--- a/src/fractal.cpp
+++ b/src/fractal.cpp
@@ -8,10 +8,6 @@ namespace log = mtl::log;
 
 namespace fractal {
 
-bool ruleset_t::tokens_full() const {
-	return m_tokens.full();
-}
-
 token_id_t ruleset_t::add_token(token_type_e type, mtl::fixed value) {
 	if (m_tokens.full()) {
 		throw mtl::length_error();