diff --git a/arduino-core/src/processing/app/helpers/StringReplacer.java b/arduino-core/src/processing/app/helpers/StringReplacer.java
index 6c90e2558..1e1dd9eab 100644
--- a/arduino-core/src/processing/app/helpers/StringReplacer.java
+++ b/arduino-core/src/processing/app/helpers/StringReplacer.java
@@ -24,9 +24,50 @@ package processing.app.helpers;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.UUID;
 
 public class StringReplacer {
 
+  public static void checkIfRequiredKeyIsMissingOrExcept(String key, String src, PreferencesMap inDict) throws PreferencesMapException {
+    // If the key is not missing -> everything is OK
+    String checkedValue = inDict.get(key);
+    if (checkedValue != null && !checkedValue.isEmpty())
+      return;
+
+    PreferencesMap dict = new PreferencesMap(inDict);
+
+    // Find a random tag that is not contained in the dictionary and the src pattern
+    String tag;
+    while (true) {
+      tag = UUID.randomUUID().toString();
+      if (src.contains(tag))
+        continue;
+      if (dict.values().contains(tag))
+        continue;
+      if (dict.keySet().contains(tag))
+        continue;
+      break;
+    }
+
+    // Inject tag inside the dictionary
+    dict.put(key, tag);
+
+    // Recursive replace with a max depth of 10 levels.
+    String res;
+    for (int i = 0; i < 10; i++) {
+      // Do a replace with dictionary
+      res = StringReplacer.replaceFromMapping(src, dict);
+      if (res.equals(src))
+        break;
+      src = res;
+    }
+
+    // If the resulting string contains the tag, then the key is required
+    if (src.contains(tag)) {
+      throw new PreferencesMapException(key);
+    }
+  }
+
   public static String[] formatAndSplit(String src, Map<String, String> dict) throws Exception {
     String res;