diff --git a/poincare/src/unit.cpp b/poincare/src/unit.cpp
index 901085695..f92b0bc7a 100644
--- a/poincare/src/unit.cpp
+++ b/poincare/src/unit.cpp
@@ -922,11 +922,15 @@ void Unit::chooseBestRepresentativeAndPrefix(double * value, double exponent, Ex
   double baseValue = *value * std::pow(node()->representative()->ratio() * std::pow(10., node()->prefix()->exponent() - node()->representative()->basePrefix()->exponent()), exponent);
   const Prefix * bestPrefix = (optimizePrefix) ? Prefix::EmptyPrefix() : nullptr;
   const Representative * bestRepresentative = node()->representative()->standardRepresentative(baseValue, exponent, reductionContext, &bestPrefix);
+  if (!optimizePrefix) {
+    bestPrefix = bestRepresentative->basePrefix();
+  }
+
   if (bestRepresentative != node()->representative()) {
     *value = *value * std::pow(node()->representative()->ratio() / bestRepresentative->ratio() * std::pow(10., bestRepresentative->basePrefix()->exponent() - node()->representative()->basePrefix()->exponent()), exponent);
     node()->setRepresentative(bestRepresentative);
   }
-  if (optimizePrefix && bestPrefix != node()->prefix()) {
+  if (bestPrefix != node()->prefix()) {
     *value = *value * std::pow(10., exponent * (node()->prefix()->exponent() - bestPrefix->exponent()));
     node()->setPrefix(bestPrefix);
   }
diff --git a/poincare/test/simplification.cpp b/poincare/test/simplification.cpp
index 8ccc7718b..32b5bf580 100644
--- a/poincare/test/simplification.cpp
+++ b/poincare/test/simplification.cpp
@@ -536,6 +536,7 @@ QUIZ_CASE(poincare_simplification_units) {
   assert_parsed_expression_simplify_to("cos(1_s/1_s)", "cos(1)");
   assert_parsed_expression_simplify_to("1_m+π_m+√(2)_m-cos(15)_m", "6.3154941288217×_m");
   assert_parsed_expression_simplify_to("√(16×_m^2)", "4×_m");
+  assert_parsed_expression_simplify_to("1×_A_kg", "2.2046226218488×_A×_lb", User, Radian, Imperial);
 }
 
 QUIZ_CASE(poincare_simplification_power) {