diff --git a/pkgs/by-name/li/libfishsound/fix-callbacks.patch b/pkgs/by-name/li/libfishsound/fix-callbacks.patch
new file mode 100644
index 000000000000..992efcf23ec8
--- /dev/null
+++ b/pkgs/by-name/li/libfishsound/fix-callbacks.patch
@@ -0,0 +1,20 @@
+--- a/src/libfishsound/flac.c
++++ b/src/libfishsound/flac.c
+@@ -106,7 +106,7 @@ fs_flac_command (FishSound * fsound, int command, void * data, int datasize)
+ #if FS_DECODE
+ static FLAC__StreamDecoderReadStatus
+ fs_flac_read_callback(const FLAC__StreamDecoder *decoder,
+-                      FLAC__byte buffer[], unsigned int *bytes,
++                      FLAC__byte buffer[], size_t *bytes,
+                       void *client_data)
+ {
+   FishSound* fsound = (FishSound*)client_data;
+@@ -346,7 +346,7 @@ dec_err:
+ #if FS_ENCODE
+ static FLAC__StreamEncoderWriteStatus
+ fs_flac_enc_write_callback(const FLAC__StreamEncoder *encoder,
+-                           const FLAC__byte buffer[], unsigned bytes,
++                           const FLAC__byte buffer[], size_t bytes,
+                            unsigned samples, unsigned current_frame,
+                            void *client_data)
+ {
diff --git a/pkgs/by-name/li/libfishsound/package.nix b/pkgs/by-name/li/libfishsound/package.nix
index 0c5ea9c4c023..63b0838b4b01 100644
--- a/pkgs/by-name/li/libfishsound/package.nix
+++ b/pkgs/by-name/li/libfishsound/package.nix
@@ -17,6 +17,10 @@ stdenv.mkDerivation rec {
     sha256 = "1iz7mn6hw2wg8ljaw74f4g2zdj68ib88x4vjxxg3gjgc5z75f2rf";
   };
 
+  patches = [
+    ./fix-callbacks.patch
+  ];
+
   propagatedBuildInputs = [
     libvorbis
     speex