3 files changed, 4 insertions, 4 deletions
diff --git a/src/audioinputengine.h b/src/audioinputengine.h
index d7ac9c9..105db49 100644
--- a/src/audioinputengine.h
+++ b/src/audioinputengine.h
@@ -40,7 +40,7 @@ public:
 
   virtual bool isMidiEngine() { return false; } 
 
-  virtual bool init(Instruments& instruments) = 0;
+  virtual bool init(const Instruments& instruments) = 0;
 
   virtual void setParm(const std::string& parm, const std::string& value) = 0;
 
diff --git a/src/audioinputenginemidi.cc b/src/audioinputenginemidi.cc
index e3cb796..e18e446 100644
--- a/src/audioinputenginemidi.cc
+++ b/src/audioinputenginemidi.cc
@@ -38,7 +38,7 @@ AudioInputEngineMidi::AudioInputEngineMidi()
   is_valid = false;
 }
 
-bool AudioInputEngineMidi::loadMidiMap(std::string file, Instruments &instruments)
+bool AudioInputEngineMidi::loadMidiMap(const std::string& file, const Instruments& instruments)
 {
   std::string f = file;
 
diff --git a/src/audioinputenginemidi.h b/src/audioinputenginemidi.h
index 36fcbaa..82121b7 100644
--- a/src/audioinputenginemidi.h
+++ b/src/audioinputenginemidi.h
@@ -43,7 +43,7 @@ public:
 
   bool isMidiEngine() { return true; } 
 
-  virtual bool init(Instruments &instruments) = 0;
+  virtual bool init(const Instruments &instruments) = 0;
 
   virtual void setParm(const std::string& parm, const std::string& value) = 0;
 
@@ -54,7 +54,7 @@ public:
   virtual void run(size_t pos, size_t len, std::vector<event_t>& events) = 0;
   virtual void post() = 0;
 
-  bool loadMidiMap(std::string file, Instruments &i);
+  bool loadMidiMap(const std::string& file, const Instruments& i);
 
   std::string midimapFile();