diff --git a/CHANGELOG.md b/CHANGELOG.md
index c8b0431e..f14a1613 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,8 @@
 * Watchlist endpoints require pagination: deprecate the variants that don't accept page and limit parameters.
 * Add warnings to `watchedAt()` setters, update existing warnings
   that [Trakt already only stores and returns minute-precision timestamps](https://github.com/trakt/trakt-api/discussions/694).
+* The 3D `Metadata` property of movies in a collection is now a number, so added `boolean is3D()` and deprecated
+  `Boolean is3d`.
 
 ## 6.17.0 - 2026-02-05
 
diff --git a/src/main/java/com/uwetrottmann/trakt5/entities/BaseEpisode.java b/src/main/java/com/uwetrottmann/trakt5/entities/BaseEpisode.java
index c7b2eb7e..3eae1d93 100644
--- a/src/main/java/com/uwetrottmann/trakt5/entities/BaseEpisode.java
+++ b/src/main/java/com/uwetrottmann/trakt5/entities/BaseEpisode.java
@@ -34,5 +34,8 @@ public class BaseEpisode {
     /** progress */
     public Boolean completed;
 
+    /**
+     * Only returned by collection endpoints.
+     */
     public Metadata metadata;
 }
diff --git a/src/main/java/com/uwetrottmann/trakt5/entities/BaseMovie.java b/src/main/java/com/uwetrottmann/trakt5/entities/BaseMovie.java
index 121c74be..9e6325e7 100644
--- a/src/main/java/com/uwetrottmann/trakt5/entities/BaseMovie.java
+++ b/src/main/java/com/uwetrottmann/trakt5/entities/BaseMovie.java
@@ -32,6 +32,9 @@ public class BaseMovie {
     public OffsetDateTime listed_at;
     public int plays;
 
+    /**
+     * Only returned by collection endpoints.
+     */
     public Metadata metadata;
 
 }
diff --git a/src/main/java/com/uwetrottmann/trakt5/entities/Metadata.java b/src/main/java/com/uwetrottmann/trakt5/entities/Metadata.java
index 6cc2f446..f07a3562 100644
--- a/src/main/java/com/uwetrottmann/trakt5/entities/Metadata.java
+++ b/src/main/java/com/uwetrottmann/trakt5/entities/Metadata.java
@@ -23,6 +23,11 @@
 import com.uwetrottmann.trakt5.enums.MediaType;
 import com.uwetrottmann.trakt5.enums.Resolution;
 
+/**
+ * Metadata of a collection item.
+ * <p>
+ * All but {@link #media_type} and {@link #resolution} are optional values.
+ */
 public class Metadata {
 
     public MediaType media_type;
@@ -30,7 +35,36 @@ public class Metadata {
     public Hdr hdr;
     public Audio audio;
     public AudioChannels audio_channels;
-    @SerializedName("3d")
+
+    /**
+     * Since 2026-03 the 3d property appears to be a number for movies.
+     * <p>
+     * This field is kept to avoid a breaking change, but its value will always be {@code null} for movies.
+     *
+     * @deprecated Use {@link #is3D()} instead.
+     */
+    @Deprecated
     public Boolean is3d;
 
+    /**
+     * Since 2026-03 appears to be 1 or null for movies. Or true and false for episodes.
+     *
+     * @see #is3D()
+     */
+    @SerializedName("3d")
+    public Object _is3D;
+
+    public boolean is3D() {
+        if (_is3D != null) {
+            if (_is3D instanceof Boolean) {
+                return (Boolean) _is3D;
+            }
+            // Numbers are deserialized by default to Double
+            if (_is3D instanceof Double) {
+                return (Double) _is3D == 1.0;
+            }
+        }
+        return false;
+    }
+
 }
diff --git a/src/test/java/com/uwetrottmann/trakt5/services/SyncTest.java b/src/test/java/com/uwetrottmann/trakt5/services/SyncTest.java
index bd86f2eb..6859aef8 100644
--- a/src/test/java/com/uwetrottmann/trakt5/services/SyncTest.java
+++ b/src/test/java/com/uwetrottmann/trakt5/services/SyncTest.java
@@ -45,6 +45,7 @@
 import com.uwetrottmann.trakt5.entities.SyncShow;
 import com.uwetrottmann.trakt5.entities.WatchlistedEpisode;
 import com.uwetrottmann.trakt5.entities.WatchlistedSeason;
+import com.uwetrottmann.trakt5.enums.Extended;
 import com.uwetrottmann.trakt5.enums.HistoryType;
 import com.uwetrottmann.trakt5.enums.Rating;
 import com.uwetrottmann.trakt5.enums.RatingsFilter;
@@ -186,13 +187,17 @@ private void assertLastActivityUpdated(LastActivityUpdated activity) {
 
     @Test
     public void test_collectionMovies() throws IOException {
-        List<BaseMovie> movies = executeCall(getTrakt().sync().collectionMovies(1, 1000, null));
+        // Get metadata to assert it can be parsed.
+        // On the test account, Star Wars: The Force Awakens has all properties set.
+        List<BaseMovie> movies = executeCall(getTrakt().sync().collectionMovies(1, 1000, Extended.METADATA));
         assertSyncMovies(movies, "collection");
     }
 
     @Test
     public void test_collectionShows() throws IOException {
-        List<BaseShow> shows = executeCall(getTrakt().sync().collectionShows(1, 1000, null));
+        // Get metadata to assert it can be parsed.
+        // On the test account, episode 1x08 of Start Trek: Starfleet Academy has all properties set.
+        List<BaseShow> shows = executeCall(getTrakt().sync().collectionShows(1, 1000, Extended.METADATA));
         assertSyncShows(shows, "collection");
     }