diff --git a/poincare/include/poincare/expression.h b/poincare/include/poincare/expression.h
index 579bd9e6a..e8a724aac 100644
--- a/poincare/include/poincare/expression.h
+++ b/poincare/include/poincare/expression.h
@@ -148,7 +148,8 @@ public:
   /* Simplification */
   static void simplify(Expression ** expressionAddress, Context & context, AngleUnit angleUnit = AngleUnit::Default);
 
-  bool containType(Type type) const;
+  typedef bool (*ExpressionTest)(const Expression * e);
+  bool recursivelyMatches(ExpressionTest test) const;
 
   /* Evaluation Engine
    * The function evaluate creates a new expression and thus mallocs memory.
diff --git a/poincare/src/expression.cpp b/poincare/src/expression.cpp
index bb04df094..b17177eda 100644
--- a/poincare/src/expression.cpp
+++ b/poincare/src/expression.cpp
@@ -95,12 +95,12 @@ Expression * Expression::deepBeautify(Context & context, AngleUnit angleUnit) {
   return e;
 }
 
-bool Expression::containType(Type t) const {
-  if (type() == t) {
+bool Expression::recursivelyMatches(ExpressionTest test) const {
+  if (test(this)) {
     return true;
   }
   for (int i = 0; i < numberOfOperands(); i++) {
-    if (operand(i)->containType(t)) {
+    if (test(operand(i))) {
       return true;
     }
   }