diff --git a/src/main/java/de/neemann/digital/core/Model.java b/src/main/java/de/neemann/digital/core/Model.java
index 8c65152b2..d7483d413 100644
--- a/src/main/java/de/neemann/digital/core/Model.java
+++ b/src/main/java/de/neemann/digital/core/Model.java
@@ -60,6 +60,7 @@ public class Model implements Iterable<Node> {
     private boolean isInitialized = false;
     private WindowPosManager windowPosManager;
     private HashSet<Node> oscillatingNodes;
+    private boolean isInvalidSignal = false;
 
     /**
      * Creates a new model
@@ -422,7 +423,8 @@ public class Model implements Iterable<Node> {
         if (signal.isValid()) {
             signals.add(signal);
             inputs.add(signal);
-        }
+        } else
+            isInvalidSignal = true;
     }
 
     /**
@@ -441,7 +443,15 @@ public class Model implements Iterable<Node> {
         if (signal.isValid()) {
             signals.add(signal);
             outputs.add(signal);
-        }
+        } else
+            isInvalidSignal = true;
+    }
+
+    /**
+     * @return true if there was an invalid signal
+     */
+    public boolean isInvalidSignal() {
+        return isInvalidSignal;
     }
 
     /**
diff --git a/src/main/java/de/neemann/digital/gui/Main.java b/src/main/java/de/neemann/digital/gui/Main.java
index bd4e826e9..c5a655b56 100644
--- a/src/main/java/de/neemann/digital/gui/Main.java
+++ b/src/main/java/de/neemann/digital/gui/Main.java
@@ -861,6 +861,13 @@ public final class Main extends JFrame implements ClosingWindowListener.ConfirmS
             public void actionPerformed(ActionEvent e) {
                 try {
                     Model model = new ModelCreator(circuitComponent.getCircuit(), library).createModel(false);
+
+                    if (model.isInvalidSignal())
+                        JOptionPane.showMessageDialog(Main.this,
+                                new LineBreaker().toHTML().breakLines(Lang.get("msg_invalidSignalsAnalysed")),
+                                Lang.get("msg_warning"),
+                                JOptionPane.WARNING_MESSAGE);
+
                     new TableDialog(Main.this, new ModelAnalyser(model).analyse(), library, shapeFactory, getBaseFileName())
                             .setVisible(true);
                     ensureModelIsStopped();
diff --git a/src/main/resources/lang/lang_de.xml b/src/main/resources/lang/lang_de.xml
index e3e05e8bd..bcc112986 100644
--- a/src/main/resources/lang/lang_de.xml
+++ b/src/main/resources/lang/lang_de.xml
@@ -921,6 +921,8 @@ Die Icons stammen aus dem Tango Desktop Project.</string>
     <string name="msg_errInFile_N">Aufgetreten in Datei {0}.</string>
     <string name="msg_affectedComponentsAre_N">Betroffen sind: {0}.</string>
     <string name="msg_signal_N">Leitung {0}</string>
+    <string name="msg_invalidSignalsAnalysed">Wenn Ein- oder Ausgänge keinen Namen haben, werden diese nicht
+        als Variablen in die Analyse einbezogen, sondern wie Konstanten behandelt!</string>
 
     <string name="ok">Ok</string>
     <string name="rot_0">0°</string>
diff --git a/src/main/resources/lang/lang_en.xml b/src/main/resources/lang/lang_en.xml
index 5fd3391fc..c7777e46c 100644
--- a/src/main/resources/lang/lang_en.xml
+++ b/src/main/resources/lang/lang_en.xml
@@ -908,6 +908,8 @@ The icons are taken from the Tango Desktop Project.</string>
     <string name="msg_errInFile_N">Occurred in file {0}.</string>
     <string name="msg_affectedComponentsAre_N">Affected are: {0}.</string>
     <string name="msg_signal_N">Signal {0}</string>
+    <string name="msg_invalidSignalsAnalysed">If inputs or outputs have no name set, they are not included
+        as variables in the analysis, but treated as constants!</string>
 
     <string name="ok">Ok</string>
     <string name="rot_0">0°</string>