diff --git a/pcm.hh b/pcm.hh
index e5c492f..1b4abfd 100644
--- a/pcm.hh
+++ b/pcm.hh
@@ -11,7 +11,7 @@ namespace DSP {
 template <typename TYPE>
 struct WritePCM
 {
-	virtual void write(TYPE *, int, int = -1) = 0;
+	virtual void write(const TYPE *, int, int = -1) = 0;
 	virtual bool good() = 0;
 	virtual void silence(int) = 0;
 	virtual int rate() = 0;
diff --git a/wav.hh b/wav.hh
index 60bd6ee..5d5ac97 100644
--- a/wav.hh
+++ b/wav.hh
@@ -206,7 +206,7 @@ public:
 		os.seekp(40);
 		writeLE(size, 4); // Subchunk2Size
 	}
-	void write(TYPE *buf, int num, int stride = -1)
+	void write(const TYPE *buf, int num, int stride = -1)
 	{
 		if (stride < 0)
 			stride = channels_;