diff --git a/package.json b/package.json
index c8b34d3b7..d5f19bd65 100644
--- a/package.json
+++ b/package.json
@@ -9,7 +9,6 @@
   "scripts": {
     "build": "vue-cli-service build",
     "serve": "vue-cli-service serve",
-    "build": "vue-cli-service build",
     "build-bundle": "vue-cli-service build --target lib --name flow-builder src/lib.ts",
     "test:unit": "vue-cli-service test:unit",
     "lint": "vue-cli-service lint",
@@ -44,6 +43,7 @@
     "plain-draggable": "^2.5.12",
     "pointer-event": "^1.0.0",
     "popper.js": "^1.16.1",
+    "scanf": "^1.1.2",
     "vue": "^2.6.11",
     "vue-class-component": "^7.2.3",
     "vue-focus": "^2.1.0",
diff --git a/src/assets/messages.json b/src/assets/messages.json
index ce99ec8d1..5c62e1b47 100644
--- a/src/assets/messages.json
+++ b/src/assets/messages.json
@@ -1,5 +1,9 @@
 {
   "en.flow-builder": {
+    "scanf-format-string-invalid": "Format String Invalid. Please refer to the documentation for scanf: https://www.php.net/manual/en/function.sscanf.php",
+    "edit-variable": "Enter Variable Name",
+    "format-string": "Format String",
+    "enter-format-string": "Enter Format String",
     "flow-name":  "Flow name",
     "flow-label": "Flow label",
     "flow-importer": "Flow importer",
@@ -1539,6 +1543,10 @@
     "youre-using-floip-expressions": "It looks like you're using FLOIP expressions, nice!"
   },
   "fr.flow-builder": {
+    "scanf-format-string-invalid": "Chaîne de format non valide. Veuillez vous référer à la documentation: https://www.php.net/manual/en/function.sscanf.php",
+    "edit-variable": "Modifier le nom de la variable",
+    "format-string": "Chaîne de format",
+    "enter-format-string": "Entrez la chaîne de format",
     "flow-name":  "Nom du flux",
     "flow-label": "Libélé du flux",
     "flow-importer": "importateur de flux",
diff --git a/src/components/interaction-designer/block-editors/FormatStringEditor.vue b/src/components/interaction-designer/block-editors/FormatStringEditor.vue
index c85e72b1c..d873a766b 100644
--- a/src/components/interaction-designer/block-editors/FormatStringEditor.vue
+++ b/src/components/interaction-designer/block-editors/FormatStringEditor.vue
@@ -2,13 +2,18 @@
   <div>
     <text-editor v-model="formatString"
         :label="'flow-builder.format-string' | trans"
-        :placeholder="'flow-builder.enter-format-string' | trans"/>
+        :placeholder="'flow-builder.enter-format-string' | trans">
+      <small class="text-danger" v-if="!isScanfSelectorValid">
+        {{'flow-builder.scanf-format-string-invalid' | trans}}
+      </small>
+    </text-editor>
   </div>
 </template>
 
 <script>
 import TextEditor from '@/components/common/TextEditor'
 import lang from '@/lib/filters/lang'
+import { sscanf } from 'scanf'
 
 export default {
   components: {
@@ -21,13 +26,24 @@ export default {
       required: true,
     },
   },
+  data() {
+    return {
+      isScanfSelectorValid: true,
+    }
+  },
   computed: {
     formatString: {
       get() {
         return this.block.config.format_string
       },
-      set(value) {
-        this.$emit('commitFormatStringChange', value)
+      set(newFormatString) {
+        try {
+          sscanf('any string', newFormatString)
+          this.isScanfSelectorValid = true
+        } catch (error) {
+          this.isScanfSelectorValid = false
+        }
+        this.$emit('commitFormatStringChange', newFormatString)
       },
     },
   },
diff --git a/src/store/flow/block-types/ConsoleIO_ReadBlockStore.ts b/src/store/flow/block-types/ConsoleIO_ReadBlockStore.ts
index 3f9b7de95..9224c9060 100644
--- a/src/store/flow/block-types/ConsoleIO_ReadBlockStore.ts
+++ b/src/store/flow/block-types/ConsoleIO_ReadBlockStore.ts
@@ -7,14 +7,23 @@ import { IdGeneratorUuidV4 } from '@floip/flow-runner/dist/domain/IdGeneratorUui
 import { IRunFlowBlock } from '@floip/flow-runner/src/model/block/IRunFlowBlock'
 import { defaults, split } from 'lodash'
 import { IFlowsState } from '../index'
+import { sscanf } from 'scanf'
 
 export const BLOCK_TYPE = 'ConsoleIO\\Read'
 
 export const getters: GetterTree<IFlowsState, IRootState> = {
   destinationVariablesFields: (state, getters, rootState, rootGetters): string[] => {
     const activeBlock = rootGetters['builder/activeBlock']
-    // TODO: correct the destination variables array according to scanf library we're using, and think about consecutive % or other error we should avoid
-    return new Array(split(activeBlock.config.format_string || '', '%').length - 1)
+    try {
+      //We don't care what string we use to test the format string
+      //...we just want to know how many scanf variables we will read.
+      //When we would only read a single variable the library only gives back one value
+      //...rather than an array so we have to force it into an array.
+      const destinationVariables = sscanf('any string', activeBlock.config.format_string || '')
+      return (typeof destinationVariables === 'object') ? destinationVariables : [destinationVariables]
+    } catch (error) {
+      return []
+    }
   },
 }
 
diff --git a/yarn.lock b/yarn.lock
index 3616b3e5f..82c0f72c0 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -14166,6 +14166,11 @@ saxes@^5.0.0:
   dependencies:
     xmlchars "^2.2.0"
 
+scanf@^1.1.2:
+  version "1.1.2"
+  resolved "https://registry.yarnpkg.com/scanf/-/scanf-1.1.2.tgz#1a11912f50f6773e0c9e1e26145b9895fdd69c07"
+  integrity sha512-AjyDCF9jrLcGl+wbH2OO0vfpMUNmv6skJuuLL/vgDUmG/0YXCT6SVBTOvZXOPAD5raJLtDtUU7v0yF79JDuAqA==
+
 scheduler@^0.19.1:
   version "0.19.1"
   resolved "https://registry.yarnpkg.com/scheduler/-/scheduler-0.19.1.tgz#4f3e2ed2c1a7d65681f4c854fa8c5a1ccb40f196"