diff --git a/src/gen/plug/_pluginreg.py b/src/gen/plug/_pluginreg.py
index 503e4dcb9..654173554 100644
--- a/src/gen/plug/_pluginreg.py
+++ b/src/gen/plug/_pluginreg.py
@@ -140,6 +140,7 @@ def valid_plugin_version(plugin_version_string):
     Checks to see if string is a valid version string for this version
     of Gramps.
     """
+    if not isinstance(plugin_version_string, basestring): return False
     dots = plugin_version_string.count(".")
     if dots == 1:
         plugin_version  = tuple([int(n) for n in