diff --git a/source/Interpreter/NamedOptionValue.cpp b/source/Interpreter/NamedOptionValue.cpp
index 6b5dd7e..4721b9d 100644
--- a/source/Interpreter/NamedOptionValue.cpp
+++ b/source/Interpreter/NamedOptionValue.cpp
@@ -156,7 +156,12 @@
     }
     else
     {
-        error.SetErrorStringWithFormat ("invalid boolean string value: '%s'\n", value_cstr);
+        if (value_cstr == NULL)
+            error.SetErrorString ("invalid boolean string value: NULL\n");
+        else if (value_cstr[0] == '\0')
+            error.SetErrorString ("invalid boolean string value <empty>\n");
+        else
+            error.SetErrorStringWithFormat ("invalid boolean string value: '%s'\n", value_cstr);
     }
     return error;
 }
@@ -303,17 +308,6 @@
     return error;
 }
 
-
-uint64_t
-OptionValueArray::GetUInt64ValueAtIndex (uint32_t idx, uint64_t fail_value, bool *success_ptr) const
-{
-    if (idx < m_values.size())
-        return m_values[idx]->GetUInt64Value (fail_value, success_ptr);
-    return fail_value;
-}
-
-
-
 //-------------------------------------------------------------------------
 // OptionValueDictionary
 //-------------------------------------------------------------------------