diff --git a/src/Python/SIP/Bindings.cpp b/src/Python/SIP/Bindings.cpp
index 47afc0d6a..3e0a7fda6 100644
--- a/src/Python/SIP/Bindings.cpp
+++ b/src/Python/SIP/Bindings.cpp
@@ -879,7 +879,7 @@ PythonXDataSeries::PythonXDataSeries()
 
 bool PythonXDataSeries::set(int i, double value)
 {
-    if (rideFile) {
+    if (!readOnly && rideFile) {
         if (!setColIdx()){
             return false;
         }