diff --git a/src/main/java/com/scienceminer/nerd/kb/db/KBDatabase.java b/src/main/java/com/scienceminer/nerd/kb/db/KBDatabase.java
index 1fce84c6..24438d72 100644
--- a/src/main/java/com/scienceminer/nerd/kb/db/KBDatabase.java
+++ b/src/main/java/com/scienceminer/nerd/kb/db/KBDatabase.java
@@ -47,6 +47,7 @@ public KBDatabase(KBEnvironment env, DatabaseType type) {
         }
         this.environment = Env.create()
                 .setMapSize(100L * 1024L * 1024L * 1024L)
+                .setMaxReaders(126)
                 .open(thePath, EnvFlags.MDB_NOTLS);
 
         db = this.environment.openDbi(type.name(), DbiFlags.MDB_CREATE);
@@ -78,6 +79,7 @@ public KBDatabase(KBEnvironment env, DatabaseType type, String name) {
         }
         this.environment = Env.create()
                 .setMapSize(100L * 1024L * 1024L * 1024L)
+                .setMaxReaders(126)
                 .open(thePath);
         db = this.environment.openDbi(this.name, DbiFlags.MDB_CREATE);
     }
diff --git a/src/main/java/com/scienceminer/nerd/kb/db/WikipediaDomainMap.java b/src/main/java/com/scienceminer/nerd/kb/db/WikipediaDomainMap.java
index c549a731..acbec142 100644
--- a/src/main/java/com/scienceminer/nerd/kb/db/WikipediaDomainMap.java
+++ b/src/main/java/com/scienceminer/nerd/kb/db/WikipediaDomainMap.java
@@ -72,6 +72,7 @@ public WikipediaDomainMap(String lang, String envPath) {
         }
         this.environment = Env.create()
                 .setMapSize(100L * 1024L * 1024L * 1024L)
+                .setMaxReaders(126)
                 .open(thePath, MDB_NOTLS);
         db = this.environment.openDbi(database_name, DbiFlags.MDB_CREATE);
     }