diff --git a/tycho-core/src/main/java/org/eclipse/tycho/core/maven/TychoMavenLifecycleParticipant.java b/tycho-core/src/main/java/org/eclipse/tycho/core/maven/TychoMavenLifecycleParticipant.java
index 47b2d56038..e3126fbe2d 100644
--- a/tycho-core/src/main/java/org/eclipse/tycho/core/maven/TychoMavenLifecycleParticipant.java
+++ b/tycho-core/src/main/java/org/eclipse/tycho/core/maven/TychoMavenLifecycleParticipant.java
@@ -34,6 +34,7 @@
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ForkJoinPool;
 import java.util.concurrent.ForkJoinTask;
+import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
@@ -104,6 +105,8 @@ public class TychoMavenLifecycleParticipant extends AbstractMavenLifecyclePartic
     @Requirement
     TychoProjectManager projectManager;
 
+    private boolean warnedAboutTychoMode;
+
     public TychoMavenLifecycleParticipant() {
         // needed for plexus
     }
@@ -361,11 +364,38 @@ private void validateUniqueBaseDirs(List<MavenProject> projects) throws MavenExe
     private static final Set<String> CLEAN_PHASES = Set.of("pre-clean", "clean", "post-clean");
 
     private boolean disableLifecycleParticipation(MavenSession session) {
+        return isMavenMode(session) || isM2E(session) || isCleanOnly(session);
+    }
+
+    private boolean isCleanOnly(MavenSession session) {
+        // disable for 'clean-only' builds. Consider that Maven can be invoked without explicit goals, if default goals are specified
+        return !session.getGoals().isEmpty() && CLEAN_PHASES.containsAll(session.getGoals());
+    }
+
+    private boolean isM2E(MavenSession session) {
+        return session.getUserProperties().containsKey("m2e.version");
+    }
+
+    private boolean isMavenMode(MavenSession session) {
         // command line property to disable Tycho lifecycle participant
-        return "maven".equals(session.getUserProperties().get("tycho.mode"))
-                || session.getUserProperties().containsKey("m2e.version")
-                // disable for 'clean-only' builds. Consider that Maven can be invoked without explicit goals, if default goals are specified
-                || (!session.getGoals().isEmpty() && CLEAN_PHASES.containsAll(session.getGoals()));
+        if ("maven".equals(session.getUserProperties().get(TychoConstants.SESSION_PROPERTY_TYCHO_MODE))) {
+            synchronized (TychoMavenLifecycleParticipant.class) {
+                if (!warnedAboutTychoMode) {
+                    warnedAboutTychoMode = true;
+                    log.warn("######## IMPORTANT #######");
+                    log.warn("Usage of " + TychoConstants.SESSION_PROPERTY_TYCHO_MODE
+                            + "=maven is deprecated and will be removed in later Tycho versions, see https://github.com/eclipse-tycho/tycho/issues/676");
+                    log.warn("######## IMPORTANT #######");
+                    try {
+                        //to give user change to see the message....
+                        TimeUnit.SECONDS.sleep(5);
+                    } catch (InterruptedException e) {
+                    }
+                }
+            }
+            return true;
+        }
+        return false;
     }
 
     private void configureComponents(MavenSession session) {