diff --git a/Content.Tests/DMProject/Tests/List/ListOr.dm b/Content.Tests/DMProject/Tests/List/ListOr.dm
new file mode 100644
index 0000000000..4983c4be3c
--- /dev/null
+++ b/Content.Tests/DMProject/Tests/List/ListOr.dm
@@ -0,0 +1,6 @@
+/proc/RunTest()
+	var/list/L1 = list("a" = 1, "b" = 2)
+	var/list/L2 = list("c" = 3, "d" = 4)
+	var/list/result = L1 | L2
+	
+	ASSERT(result ~= list("a" = 1, "b" = 2, "c" = 3, "d" = 4))
\ No newline at end of file
diff --git a/OpenDreamRuntime/Objects/Types/DreamList.cs b/OpenDreamRuntime/Objects/Types/DreamList.cs
index 8611f126a2..0c9a653b1f 100644
--- a/OpenDreamRuntime/Objects/Types/DreamList.cs
+++ b/OpenDreamRuntime/Objects/Types/DreamList.cs
@@ -323,7 +323,7 @@ public virtual int GetLength() {
     }
 
     public DreamList Union(DreamList other) {
-        DreamList newList = new DreamList(ObjectDefinition, _values.Union(other.GetValues()).ToList(), null);
+        DreamList newList = new DreamList(ObjectDefinition, _values.Union(other.EnumerateValues()).ToList(), IsAssociative ? new(_associativeValues!) : null);
         foreach ((DreamValue key, DreamValue value) in other.GetAssociativeValues()) {
             newList.SetValue(key, value);
         }