diff --git a/src/wavefile.c b/src/wavefile.c
index 34e7375..ef1e4b2 100644
--- a/src/wavefile.c
+++ b/src/wavefile.c
@@ -1,3 +1,10 @@
+/**
+ * Copyright (c) 2017 rnlf
+ *
+ * This library is free software; you can redistribute it and/or modify it
+ * under the terms of the MIT license. See LICENSE for details.
+ */
+
 #include <string.h>
 #include "filesystem.h"
 #include "wavefile.h"
@@ -33,6 +40,11 @@ char const* wavefile_load(source_t *source, char const *filename) {
   char const *err = 0;
   uint8_t *waveData = filesystem_read(filename, &fileSize);
 
+  if(waveData == NULL) {
+    err = "Could not read WAV file";
+    goto fail;
+  }
+
   waveheader_t const* header = (waveheader_t const*)waveData;
 
   if(header->chunkId != RIFF_CHUNK_ID
diff --git a/src/wavefile.h b/src/wavefile.h
index e8db8d5..f462a27 100644
--- a/src/wavefile.h
+++ b/src/wavefile.h
@@ -1,5 +1,15 @@
-#pragma once
+/**
+ * Copyright (c) 2017 rnlf
+ *
+ * This library is free software; you can redistribute it and/or modify it
+ * under the terms of the MIT license. See LICENSE for details.
+ */
+
+#ifndef WAVEFILE_H
+#define WAVEFILE_H
 
 #include "source.h"
 
 char const* wavefile_load(source_t *source, char const *filename);
+
+#endif