diff --git a/include/crpropa/Module.h b/include/crpropa/Module.h
index e21c6b555..e62f5b14e 100644
--- a/include/crpropa/Module.h
+++ b/include/crpropa/Module.h
@@ -60,8 +60,11 @@ class AbstractCondition: public Module {
 	void setRejectFlag(std::string key, std::string value);
 	void setAcceptFlag(std::string key, std::string value);
 
-	void printRejectFlag();
-	void printAcceptFlag();
+	// return the reject flag (key & value), delimiter is the "&".
+	std::string getRejectFlag();
+
+	// return the accept flag (key & value), delimiter is the "&"
+	std::string getAcceptFlag();
 };
 
 /**
diff --git a/src/Module.cpp b/src/Module.cpp
index aabbfd694..3af768bf9 100644
--- a/src/Module.cpp
+++ b/src/Module.cpp
@@ -76,12 +76,14 @@ void AbstractCondition::setAcceptFlag(std::string key, std::string value) {
 	acceptFlagValue = value;
 }
 
-void AbstractCondition::printRejectFlag() {
-	std::cout << "rejectKey: " << rejectFlagKey << " with flag: " << rejectFlagValue << "\n";
+std::string AbstractCondition::getRejectFlag() {
+	std::string out = rejectFlagKey + "&" + rejectFlagValue; 
+	return out;
 }
 
-void AbstractCondition::printAcceptFlag() {
-	std::cout << "acceptKey: " << acceptFlagKey << " with flag: " << acceptFlagValue << "\n";
+std::string AbstractCondition::getAcceptFlag() {
+	std::string out = acceptFlagKey + "&" + acceptFlagValue;
+	return out;
 }