diff --git a/CHANGES.rst b/CHANGES.rst
index 0d674ee..d5ca107 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -4,7 +4,8 @@ Changelog
 2.0.2 (unreleased)
 ------------------
 
-- Nothing changed yet.
+- Fix JSON call URL in virtual hosted environments. Fixes #37
+  [erral]
 
 
 2.0.1 (2021-09-16)
diff --git a/src/plone/formwidget/masterselect/widget.py b/src/plone/formwidget/masterselect/widget.py
index 200e8a5..94206e9 100644
--- a/src/plone/formwidget/masterselect/widget.py
+++ b/src/plone/formwidget/masterselect/widget.py
@@ -70,7 +70,12 @@ def getSlaves(self):
             yield slave.copy()
 
     def renderJS(self):
-        url = '/'.join(self.request.physicalPathFromURL(self.request.getURL()))
+        url = "/".join(
+            [""]
+            + self.request.physicalPathToVirtualPath(
+                self.request.physicalPathFromURL(self.request.getURL())
+            ),
+        )
         widgetURL = url + '/++widget++%s/@@masterselect-jsonvalue' % self.__name__
 
         for slave in self.getSlaves():