diff --git a/src/image.zig b/src/image.zig
index 7ba72b1..00b83b8 100644
--- a/src/image.zig
+++ b/src/image.zig
@@ -54,12 +54,6 @@ fn swrite(file: *c.SNDFILE, buf: [*]f32, frames: i64) !void {
     }
 }
 
-fn getEndPos(path: []const u8) !usize {
-    var file = try std.fs.File.openRead(path);
-    defer file.close();
-    return file.getEndPos();
-}
-
 fn temporaryName(allocator: *std.mem.Allocator) ![]u8 {
     const template_start = "/temp/temp_";
     const template = "/tmp/temp_XXXXXXXX";
@@ -125,6 +119,7 @@ pub const Image = struct {
         var image = try allocator.create(Image);
 
         std.debug.assert(in_fmt.frames > i64(0));
+        std.debug.assert(in_fmt.seekable == i32(1));
 
         image.* = Image{
             .allocator = allocator,
@@ -167,10 +162,12 @@ pub const Image = struct {
     fn copyBytes(
         self: *Image,
         out_file: *c.SNDFILE,
-        buf: []f32,
         start: usize,
         end: usize,
     ) !void {
+        var buf = try self.allocator.alloc(f32, BufferSize);
+        defer self.allocator.free(buf);
+
         const total_bytes = end - start;
         var i: usize = start;
 
@@ -287,13 +284,9 @@ pub const Image = struct {
         // - plugin
         // - post-plugin
 
-        var file_copy_buf = try self.allocator.alloc(f32, BufferSize);
-        defer self.allocator.free(file_copy_buf);
-
         // pre-plugin copy, merged with bmp header copy
         try self.copyBytes(
             out_file,
-            file_copy_buf,
             usize(0),
             seek_pos.start,
         );
@@ -322,7 +315,6 @@ pub const Image = struct {
         // post-plugin copy
         try self.copyBytes(
             out_file,
-            file_copy_buf,
             seek_pos.end + 1,
             self.frames,
         );
@@ -371,13 +363,9 @@ pub const Image = struct {
         // - CUSTOM plugin
         // - post-plugin
 
-        var file_copy_buf = try self.allocator.alloc(f32, BufferSize);
-        defer self.allocator.free(file_copy_buf);
-
         // pre-plugin copy, merged with bmp header copy
         try self.copyBytes(
             out_file,
-            file_copy_buf,
             usize(0),
             seek_pos.start,
         );
@@ -406,7 +394,6 @@ pub const Image = struct {
         // post-plugin copy
         try self.copyBytes(
             out_file,
-            file_copy_buf,
             seek_pos.end + 1,
             self.frames,
         );