diff --git a/400_xowa/src/gplx/xowa/xtns/wbases/stores/Wbase_pid_mgr.java b/400_xowa/src/gplx/xowa/xtns/wbases/stores/Wbase_pid_mgr.java
index 51c4a3575..aae21c3a2 100644
--- a/400_xowa/src/gplx/xowa/xtns/wbases/stores/Wbase_pid_mgr.java
+++ b/400_xowa/src/gplx/xowa/xtns/wbases/stores/Wbase_pid_mgr.java
@@ -38,13 +38,15 @@ public class Wbase_pid_mgr {	// EX: "en|road_map" -> 15 ("Property:P15")
 		byte[] pid_key = Bry_.Add(lang_key, Byte_ascii.Pipe_bry, pid_name);
 
 		// get from cache
-		int rv = cache.Get_as_int_or(pid_key, -1);
-		if (rv == -1) {
-			// get from db
-			rv = wbase_mgr.Wdata_wiki().Db_mgr().Load_mgr().Load_pid(lang_key, pid_name);
-			if (rv == Wbase_pid.Id_null) rv = Wbase_pid.Id_null;
-			Add(pid_key, rv);
+		synchronized (cache)  {
+			int rv = cache.Get_as_int_or(pid_key, -1);
+			if (rv == -1) {
+				// get from db
+				rv = wbase_mgr.Wdata_wiki().Db_mgr().Load_mgr().Load_pid(lang_key, pid_name);
+				if (rv == Wbase_pid.Id_null) rv = Wbase_pid.Id_null;
+				Add(pid_key, rv);
+			}
+			return rv;
 		}
-		return rv;
 	}
 }
diff --git a/400_xowa/src/gplx/xowa/xtns/wbases/stores/Wbase_qid_mgr.java b/400_xowa/src/gplx/xowa/xtns/wbases/stores/Wbase_qid_mgr.java
index 332dbcffa..6b361f394 100644
--- a/400_xowa/src/gplx/xowa/xtns/wbases/stores/Wbase_qid_mgr.java
+++ b/400_xowa/src/gplx/xowa/xtns/wbases/stores/Wbase_qid_mgr.java
@@ -39,14 +39,16 @@ public class Wbase_qid_mgr {// EX: "enwiki|0|Earth" -> "Q2"
 		byte[] key = Bry_.Add(wdata_wiki_abrv, Byte_ascii.Pipe_bry, ttl.Ns().Num_bry(), Byte_ascii.Pipe_bry, ttl.Page_db());
 
 		// get from cache
-		byte[] rv = (byte[])cache.Get_by(key);
-		if (rv == null) {
-			// get from db
-			rv = wbase_mgr.Wdata_wiki().Db_mgr().Load_mgr().Load_qid(wdata_wiki_abrv, ttl.Ns().Id(), ttl.Page_db());
-			byte[] val_for_hash = rv == null ? Bry_.Empty : rv;		// JAVA: hashtable does not accept null as value; use Bry_.Empty
-			this.Add(key, val_for_hash);							// NOTE: if not in db, will insert Bry_.Empty; DATE:2014-07-23
+		synchronized (cache) {
+			byte[] rv = (byte[])cache.Get_by(key);
+			if (rv == null) {
+				// get from db
+				rv = wbase_mgr.Wdata_wiki().Db_mgr().Load_mgr().Load_qid(wdata_wiki_abrv, ttl.Ns().Id(), ttl.Page_db());
+				byte[] val_for_hash = rv == null ? Bry_.Empty : rv;		// JAVA: hashtable does not accept null as value; use Bry_.Empty
+				this.Add(key, val_for_hash);							// NOTE: if not in db, will insert Bry_.Empty; DATE:2014-07-23
+			}
+			return Bry_.Len_eq_0(rv) ? null : rv;						// JAVA: convert Bry_.Empty to null which is what callers expect
 		}
-		return Bry_.Len_eq_0(rv) ? null : rv;						// JAVA: convert Bry_.Empty to null which is what callers expect
 	}
 	private void Add(byte[] key, byte[] val) {
 		synchronized (cache) { // LOCK:app-level