diff --git a/poincare/src/derivative.cpp b/poincare/src/derivative.cpp
index 660d7b13b..536c71723 100644
--- a/poincare/src/derivative.cpp
+++ b/poincare/src/derivative.cpp
@@ -50,7 +50,7 @@ Evaluation<T> DerivativeNode::templatedApproximate(ApproximationContext approxim
   }
 
   T error = sizeof(T) == sizeof(double) ? DBL_MAX : FLT_MAX;
-  T result;
+  T result = 1.0;
   T h = k_minInitialRate;
   static T tenEpsilon = sizeof(T) == sizeof(double) ? 10.0*DBL_EPSILON : 10.0f*FLT_EPSILON;
   do {