diff --git a/src/Configuration.php b/src/Configuration.php
index 11237354..0018ad9a 100644
--- a/src/Configuration.php
+++ b/src/Configuration.php
@@ -713,7 +713,7 @@ public function getHistorySize()
      */
     public function setEraseDuplicates(bool $value)
     {
-        $this->eraseDuplicates = (bool) $value;
+        $this->eraseDuplicates = $value;
     }
 
     /**
@@ -819,7 +819,7 @@ public function getReadline(): Readline\Readline
             $this->readline = new $className(
                 $this->getHistoryFile(),
                 $this->getHistorySize(),
-                $this->getEraseDuplicates()
+                $this->getEraseDuplicates() ?? false
             );
         }
 
diff --git a/src/Readline/Transient.php b/src/Readline/Transient.php
index cbf01e20..e5bb9ba1 100644
--- a/src/Readline/Transient.php
+++ b/src/Readline/Transient.php
@@ -50,7 +50,7 @@ public function __construct($historyFile = null, $historySize = 0, $eraseDups =
         // don't do anything with the history file...
         $this->history = [];
         $this->historySize = $historySize;
-        $this->eraseDups = $eraseDups;
+        $this->eraseDups = $eraseDups ?? false;
     }
 
     /**