diff --git a/slsDetectorSoftware/multiSlsDetector/multiSlsDetector.cpp b/slsDetectorSoftware/multiSlsDetector/multiSlsDetector.cpp
index 85ce11d61..0a2b99ced 100644
--- a/slsDetectorSoftware/multiSlsDetector/multiSlsDetector.cpp
+++ b/slsDetectorSoftware/multiSlsDetector/multiSlsDetector.cpp
@@ -610,7 +610,7 @@ slsDetector* multiSlsDetector::getSlsDetector(unsigned int pos) {
 	return 0;
 }
 
-slsDetector *multiSlsDetector::operator()(int pos) {
+slsDetector *multiSlsDetector::operator()(int pos) const {
 	if (pos >= 0 && pos < (int)detectors.size())
 		return detectors[pos];
 	return NULL;
diff --git a/slsDetectorSoftware/multiSlsDetector/multiSlsDetector.h b/slsDetectorSoftware/multiSlsDetector/multiSlsDetector.h
index 7b5353fd0..dd6afede9 100644
--- a/slsDetectorSoftware/multiSlsDetector/multiSlsDetector.h
+++ b/slsDetectorSoftware/multiSlsDetector/multiSlsDetector.h
@@ -491,7 +491,7 @@ public:
 	 * @param pos position in the multi list
 	 * @returns slsDetector object
 	 */
-	slsDetector *operator()(int pos);
+	slsDetector *operator()(int pos) const;
 
 	/**
 	 * Free shared memory from the command line