diff --git a/src/java/com/samskivert/jdbc/depot/DepotMarshaller.java b/src/java/com/samskivert/jdbc/depot/DepotMarshaller.java
index 4b70f2f..0697d21 100644
--- a/src/java/com/samskivert/jdbc/depot/DepotMarshaller.java
+++ b/src/java/com/samskivert/jdbc/depot/DepotMarshaller.java
@@ -358,7 +358,9 @@ public class DepotMarshaller<T extends PersistentRecord>
             int nulls = 0;
             for (int ii = 0; ii < _pkColumns.size(); ii++) {
                 FieldMarshaller<?> field = _pkColumns.get(ii);
-                if ((values[ii] = (Comparable<?>)field.getField().get(object)) == null) {
+                values[ii] = (Comparable<?>)field.getField().get(object);
+                if (values[ii] == null ||
+                    (values[ii] instanceof Number && ((Number)values[ii]).intValue() == 0)) {
                     nulls++;
                 }
             }
@@ -474,14 +476,14 @@ public class DepotMarshaller<T extends PersistentRecord>
     }
 
     /**
-     * Go through the registered {@link ValueGenerator}s for our persistent object and run the
-     * ones that match the current postFactum phase, filling in the fields on the supplied object
-     * while we go. This method used to generate a key; that is now a separate step.
+     * Go through the registered {@link ValueGenerator}s for our persistent object and run the ones
+     * that match the current postFactum phase, filling in the fields on the supplied object while
+     * we go.
      *
-     * The return value is only non-empty for the !postFactum phase, in which case it is a set
-     * of field names that are associated with {@link IdentityValueGenerator}, because these need
-     * special handling in the INSERT (specifically, 'DEFAULT' must be supplied as a value in
-     * the eventual SQL).
+     * The return value is only non-empty for the !postFactum phase, in which case it is a set of
+     * field names that are associated with {@link IdentityValueGenerator}, because these need
+     * special handling in the INSERT (specifically, 'DEFAULT' must be supplied as a value in the
+     * eventual SQL).
      */
     public Set<String> generateFieldValues (
         Connection conn, DatabaseLiaison liaison, Object po, boolean postFactum)
diff --git a/src/java/com/samskivert/jdbc/depot/DepotRepository.java b/src/java/com/samskivert/jdbc/depot/DepotRepository.java
index d6fa9f3..95b9eb9 100644
--- a/src/java/com/samskivert/jdbc/depot/DepotRepository.java
+++ b/src/java/com/samskivert/jdbc/depot/DepotRepository.java
@@ -315,12 +315,11 @@ public abstract class DepotRepository
         return _ctx.invoke(new CachingModifier<T>(record, key, key) {
             @Override
             public int invoke (Connection conn, DatabaseLiaison liaison) throws SQLException {
-                // set any auto-generated column values
-                Set<String> identityFields =
-                    marsh.generateFieldValues(conn, liaison, _result, false);
-
                 // if needed, update our modifier's key so that it can cache our results
+                Set<String> identityFields = Collections.emptySet();
                 if (_key == null) {
+                    // set any auto-generated column values
+                    identityFields = marsh.generateFieldValues(conn, liaison, _result, false);
                     updateKey(marsh.getPrimaryKey(_result, false));
                 }
 
@@ -329,15 +328,13 @@ public abstract class DepotRepository
                 PreparedStatement stmt = builder.prepare(conn);
                 try {
                     int mods = stmt.executeUpdate();
-
-                    // run any post-factum value generators
-                    marsh.generateFieldValues(conn, liaison, _result, true);
-
-                    // and check once more if a key now exists
+                    // run any post-factum value generators and potentially generate our key
                     if (_key == null) {
+                        marsh.generateFieldValues(conn, liaison, _result, true);
                         updateKey(marsh.getPrimaryKey(_result, false));
                     }
                     return mods;
+
                 } finally {
                     JDBCUtil.close(stmt);
                 }
@@ -739,13 +736,12 @@ public abstract class DepotRepository
                         JDBCUtil.close(stmt);
                     }
 
-                    // if the update modified zero rows or the primary key was obviously unset, do
-                    // an insertion: first, set any auto-generated column values
-                    Set<String> identityFields =
-                        marsh.generateFieldValues(conn, liaison, _result, false);
-
-                    // update our modifier's key so that it can cache our results
+                    // if the update modified zero rows or the primary key was unset, insert
+                    Set<String> identityFields = Collections.emptySet();
                     if (_key == null) {
+                        // first, set any auto-generated column values
+                        identityFields = marsh.generateFieldValues(conn, liaison, _result, false);
+                        // update our modifier's key so that it can cache our results
                         updateKey(marsh.getPrimaryKey(_result, false));
                     }
 
@@ -754,11 +750,9 @@ public abstract class DepotRepository
                     stmt = builder.prepare(conn);
                     int mods = stmt.executeUpdate();
 
-                    // run any post-factum value generators
-                    marsh.generateFieldValues(conn, liaison, _result, true);
-
-                    // and check once more if a key now exists
+                    // run any post-factum value generators and potentially generate our key
                     if (_key == null) {
+                        marsh.generateFieldValues(conn, liaison, _result, true);
                         updateKey(marsh.getPrimaryKey(_result, false));
                     }
                     created[0] = true;