diff --git a/src/Markov.hpp b/src/Markov.hpp
index 30c3b07..1562e59 100644
--- a/src/Markov.hpp
+++ b/src/Markov.hpp
@@ -21,7 +21,7 @@ public:
 	std::string regurgitate(int lines=1, std::string start="");
 	
 protected:
-	virtual void swallowLine(std::string line) =0;
+	virtual void swallowLine(std::string& line) =0;
 	virtual std::string regurgitateLine(std::string start="") =0;
 };
 
diff --git a/src/MarkovMatrix.cpp b/src/MarkovMatrix.cpp
index 6350389..0214255 100644
--- a/src/MarkovMatrix.cpp
+++ b/src/MarkovMatrix.cpp
@@ -15,7 +15,7 @@ MarkovMatrix::~MarkovMatrix()
 }
 
 
-void MarkovMatrix::feed(std::string line)
+void MarkovMatrix::feed(std::string& line)
 {
 	for (int i=0; i<=int(line.size()); ++i) {
 		int pos = std::max(i-this->length, 0);
diff --git a/src/MarkovMatrix.hpp b/src/MarkovMatrix.hpp
index 9c6869e..2b5627f 100644
--- a/src/MarkovMatrix.hpp
+++ b/src/MarkovMatrix.hpp
@@ -11,7 +11,7 @@ public:
 	MarkovMatrix(int length);
 	~MarkovMatrix();
 	
-	void feed(std::string line);
+	void feed(std::string& line);
 	void reset(int length=0); // reset the matrix, length>0 -> set a new length
 	std::map<std::string, int> hiccup(std::string& previous);
 	
diff --git a/src/SimpleMarkov.cpp b/src/SimpleMarkov.cpp
index 4428d3e..8c2465c 100644
--- a/src/SimpleMarkov.cpp
+++ b/src/SimpleMarkov.cpp
@@ -54,7 +54,7 @@ void SimpleMarkov::throwUp()
 }
 
 
-void SimpleMarkov::swallowLine(std::string line)
+void SimpleMarkov::swallowLine(std::string& line)
 {
 	this->matrix.feed(line);
 }
diff --git a/src/SimpleMarkov.hpp b/src/SimpleMarkov.hpp
index 09d2998..3d7c4d7 100644
--- a/src/SimpleMarkov.hpp
+++ b/src/SimpleMarkov.hpp
@@ -21,7 +21,7 @@ public:
 	virtual void throwUp(); // empty the belly of previous text
 	
 private:
-	virtual void swallowLine(std::string line);
+	virtual void swallowLine(std::string& line);
 	virtual std::string regurgitateLine(std::string start="");
 	
 	MarkovMatrix matrix;