diff --git a/poincare/src/addition.cpp b/poincare/src/addition.cpp
index 05eb97101..11f0fc709 100644
--- a/poincare/src/addition.cpp
+++ b/poincare/src/addition.cpp
@@ -389,11 +389,25 @@ Expression Addition::factorizeOnCommonDenominator(ExpressionNode::ReductionConte
   Power inverseDenominator = Power::Builder(commonDenominator, Rational::Builder(-1));
   Multiplication result = Multiplication::Builder(numerator, inverseDenominator);
 
+  /* To simplify the numerator and the denominator, we allow symbolic
+   * computation: all unwanted symbols should have already disappeared by now,
+   * and if we checked again for symbols we might find "paramter" symbols
+   * disconnected from the parametered expression, which would be replaed with
+   * undef.
+   * Example: int((ℯ^(-x))-x^(0.5), x, 0, 3), when creating the common
+   * denominator for the integrand. */
+  ExpressionNode::ReductionContext contextWithSymbolicComputation = ExpressionNode::ReductionContext(
+      reductionContext.context(),
+      reductionContext.complexFormat(),
+      reductionContext.angleUnit(),
+      reductionContext.target(),
+      true);
+
   // Step 4: Simplify the numerator
-  numerator.shallowReduce(reductionContext);
+  numerator.shallowReduce(contextWithSymbolicComputation);
 
   // Step 5: Simplify the denominator (in case it's a rational number)
-  inverseDenominator.deepReduce(reductionContext);
+  inverseDenominator.deepReduce(contextWithSymbolicComputation);
 
   /* Step 6: We simplify the resulting multiplication forbidding any
    * distribution of multiplication on additions (to avoid an infinite loop).