diff --git a/src/main/java/com/samskivert/depot/PersistenceContext.java b/src/main/java/com/samskivert/depot/PersistenceContext.java
index 78bdc4c..51f7193 100644
--- a/src/main/java/com/samskivert/depot/PersistenceContext.java
+++ b/src/main/java/com/samskivert/depot/PersistenceContext.java
@@ -267,7 +267,7 @@ public class PersistenceContext
         Class<T> type, SchemaMigration migration)
     {
         DepotMarshaller<T> marshaller = getRawMarshaller(type);
-        marshaller.requireInitialized(
+        marshaller.requireNotInitialized(
             "Migrations must be registered before initializeRepositories() is called.");
         marshaller.registerMigration(migration);
     }
diff --git a/src/main/java/com/samskivert/depot/impl/DepotMarshaller.java b/src/main/java/com/samskivert/depot/impl/DepotMarshaller.java
index 497b4e5..83e545d 100644
--- a/src/main/java/com/samskivert/depot/impl/DepotMarshaller.java
+++ b/src/main/java/com/samskivert/depot/impl/DepotMarshaller.java
@@ -456,10 +456,11 @@ public class DepotMarshaller<T extends PersistentRecord> implements QueryMarshal
     }
 
     /**
-     * Throws {@link IllegalStateException} with {@code msg} if this marshaller is not initialized.
+     * Throws {@link IllegalStateException} with {@code msg} if this marshaller is already
+     * initialized.
      */
-    public synchronized void requireInitialized (String msg) {
-        if (_meta == null) throw new IllegalStateException(msg);
+    public synchronized void requireNotInitialized (String msg) {
+        if (_meta != null) throw new IllegalStateException(msg);
     }
 
     /**