diff --git a/source/engine/evaluation.js b/source/engine/evaluation.js
index b15556d14..03d3771c5 100644
--- a/source/engine/evaluation.js
+++ b/source/engine/evaluation.js
@@ -79,6 +79,13 @@ export let evaluateArrayWithFilter = (evaluationFilter, reducer, start) => (
 	return rewriteNode(node, nodeValue, explanation, missingVariables)
 }
 
+export let defaultNode = nodeValue => ({
+	nodeValue,
+	// eslint-disable-next-line
+	jsx: nodeValue => <span className="value">{nodeValue}</span>,
+	isDefault: true
+})
+
 export let parseObject = (recurse, objectShape, value) => {
 	let recurseOne = key => defaultValue => {
 		if (!value[key] && !defaultValue)
diff --git a/source/engine/mecanisms.js b/source/engine/mecanisms.js
index ab844fb80..d4383c6d3 100644
--- a/source/engine/mecanisms.js
+++ b/source/engine/mecanisms.js
@@ -48,7 +48,8 @@ import {
 	collectNodeMissing,
 	mergeAllMissing,
 	mergeMissing,
-	bonus
+	bonus,
+	defaultNode
 } from './evaluation'
 import {
 	findRuleByName,
@@ -68,12 +69,6 @@ import { trancheValue } from './mecanisms/barème'
 import buildSelectionView from './mecanismViews/Selection'
 import uniroot from './uniroot'
 
-let constantNode = constant => ({
-	nodeValue: constant,
-	// eslint-disable-next-line
-	jsx: nodeValue => <span className="value">{nodeValue}</span>
-})
-
 let decompose = (recurse, k, v) => {
 	let subProps = dissoc('composantes')(v),
 		explanation = v.composantes.map(c => ({
@@ -583,8 +578,8 @@ export let mecanismSum = (recurse, k, v) => {
 export let mecanismReduction = (recurse, k, v) => {
 	let objectShape = {
 		assiette: false,
-		abattement: constantNode(0),
-		franchise: constantNode(0),
+		abattement: defaultNode(0),
+		franchise: defaultNode(0)
 	}
 
 	let effect = ({ assiette, abattement, franchise, décote }) => {
@@ -650,9 +645,9 @@ export let mecanismProduct = (recurse, k, v) => {
 
 	let objectShape = {
 		assiette: false,
-		taux: constantNode(1),
-		facteur: constantNode(1),
-		plafond: constantNode(Infinity)
+		taux: defaultNode(1),
+		facteur: defaultNode(1),
+		plafond: defaultNode(Infinity)
 	}
 	let effect = ({ assiette, taux, facteur, plafond }) => {
 		let mult = (base, rate, facteur, plafond) =>
@@ -684,7 +679,7 @@ export let mecanismProduct = (recurse, k, v) => {
 						</span>
 						<span className="value">{makeJsx(explanation.assiette)}</span>
 					</li>
-					{explanation.taux.explanation && (
+					{!explanation.taux.isDefault && (
 						<li key="taux">
 							<span className="key">
 								<Trans>taux</Trans>:{' '}
@@ -692,7 +687,7 @@ export let mecanismProduct = (recurse, k, v) => {
 							<span className="value">{makeJsx(explanation.taux)}</span>
 						</li>
 					)}
-					{explanation.facteur.explanation && (
+					{!explanation.facteur.isDefault && (
 						<li key="facteur">
 							<span className="key">
 								<Trans>facteur</Trans>:{' '}
@@ -700,7 +695,7 @@ export let mecanismProduct = (recurse, k, v) => {
 							<span className="value">{makeJsx(explanation.facteur)}</span>
 						</li>
 					)}
-					{explanation.plafond.explanation && (
+					{!explanation.plafond.isDefault && (
 						<li key="plafond">
 							<span className="key">
 								<Trans>plafond</Trans>:{' '}
@@ -800,7 +795,7 @@ export let mecanismScale = (recurse, k, v) => {
 	let tranches = desugarScale(recurse)(v['tranches']),
 		objectShape = {
 			assiette: false,
-			multiplicateur: constantNode(1)
+			multiplicateur: defaultNode(1)
 		}
 
 	let effect = ({ assiette, multiplicateur: multiplicateur, tranches }) => {
@@ -831,7 +826,7 @@ export let mecanismScale = (recurse, k, v) => {
 export let mecanismContinuousScale = (recurse, k, v) => {
 	let objectShape = {
 		assiette: false,
-		multiplicateur: constantNode(1)
+		multiplicateur: defaultNode(1)
 	}
 	let effect = ({ assiette, multiplicateur, points }) => {
 		if (anyNull([assiette, multiplicateur])) return null
diff --git a/test/mécanismes/multiplication.yaml b/test/mécanismes/multiplication.yaml
index 1dcfec6ea..9327ab07a 100644
--- a/test/mécanismes/multiplication.yaml
+++ b/test/mécanismes/multiplication.yaml
@@ -84,18 +84,21 @@
       valeur attendue: 1
 
 
-# TODO implémenter les taux variables
-# - nom: mon taux
-#   format: pourcentage
-# - test: Multiplication simple
-#   formule:
-#     multiplication:
-#       assiette: mon assiette
-#       taux: mon taux
-#
-#   exemples:
-#     - nom: exemple
-#       situation:
-#         mon assiette: 100
-#         mon taux: 3%
-#       valeur attendue: 3
+# This should work, but with the use of objectShape & co, the short circuits are not performed
+- test: Multiplication complète
+  formule:
+    multiplication:
+      assiette: mon assiette
+      facteur: mon facteur
+      plafond: mon plafond
+      taux: 0.5%
+
+  exemples:
+    - nom: Assiette manquante
+      situation:
+        mon facteur: 0
+        mon plafond: 100
+      valeur attendue: 0
+      variables manquantes: []
+
+