diff --git a/src/driver/freenas/index.js b/src/driver/freenas/index.js
index 491b334..19c8ba0 100644
--- a/src/driver/freenas/index.js
+++ b/src/driver/freenas/index.js
@@ -295,12 +295,16 @@ class FreeNASDriver extends ControllerZfsSshBaseDriver {
           ? this.options.iscsi.extentRpm
           : "SSD";
 
-        const extentAvailThreshold = this.options.iscsi.hasOwnProperty(
+        let extentAvailThreshold = this.options.iscsi.hasOwnProperty(
           "extentAvailThreshold"
         )
-          ? this.options.iscsi.extentAvailThreshold
+          ? Number(this.options.iscsi.extentAvailThreshold)
           : null;
 
+        if (!(extentAvailThreshold > 0 && extentAvailThreshold <= 100)) {
+          extentAvailThreshold = null;
+        }
+
         switch (apiVersion) {
           case 1: {
             response = await httpClient.get(