diff --git a/src/read_iter.rs b/src/adapted_iter.rs
similarity index 55%
rename from src/read_iter.rs
rename to src/adapted_iter.rs
index 35e4e08..3f9befc 100644
--- a/src/read_iter.rs
+++ b/src/adapted_iter.rs
@@ -1,24 +1,24 @@
 use crate::adapters::AdaptInfo;
 
 // TODO: using iterator trait possible?? should basically be Iterator<AdaptInfo>
-pub trait ReadIter {
+pub trait AdaptedFilesIter {
     // next takes a 'a-lived reference and returns an AdaptInfo that lives as long as the reference
     fn next<'a>(&'a mut self) -> Option<AdaptInfo<'a>>;
 }
 
 /// A single AdaptInfo
-pub struct SingleReadIter<'a> {
+pub struct SingleAdaptedFileAsIter<'a> {
     ai: Option<AdaptInfo<'a>>,
 }
-impl SingleReadIter<'_> {
-    pub fn new<'a>(ai: AdaptInfo<'a>) -> SingleReadIter<'a> {
-        SingleReadIter { ai: Some(ai) }
+impl SingleAdaptedFileAsIter<'_> {
+    pub fn new<'a>(ai: AdaptInfo<'a>) -> SingleAdaptedFileAsIter<'a> {
+        SingleAdaptedFileAsIter { ai: Some(ai) }
     }
 }
-impl ReadIter for SingleReadIter<'_> {
+impl AdaptedFilesIter for SingleAdaptedFileAsIter<'_> {
     fn next<'a>(&'a mut self) -> Option<AdaptInfo<'a>> {
         self.ai.take()
     }
 }
 
-pub type ReadIterBox<'a> = Box<dyn ReadIter + 'a>;
+pub type AdaptedFilesIterBox<'a> = Box<dyn AdaptedFilesIter + 'a>;
diff --git a/src/adapters.rs b/src/adapters.rs
index 3840c51..cb744bd 100644
--- a/src/adapters.rs
+++ b/src/adapters.rs
@@ -9,7 +9,7 @@ pub mod spawning;
 // pub mod tesseract;
 // pub mod writing;
 pub mod zip;
-use crate::{config::RgaConfig, matching::*, read_iter::ReadIterBox};
+use crate::{adapted_iter::AdaptedFilesIterBox, config::RgaConfig, matching::*};
 use anyhow::*;
 // use custom::builtin_spawning_adapters;
 //use custom::CustomAdapterConfig;
@@ -84,7 +84,7 @@ pub trait FileAdapter: GetMetadata {
         &self,
         a: AdaptInfo<'a>,
         detection_reason: &FileMatcher,
-    ) -> Result<ReadIterBox<'a>>;
+    ) -> Result<AdaptedFilesIterBox<'a>>;
 }
 
 pub struct AdaptInfo<'a> {
diff --git a/src/adapters/custom.rs b/src/adapters/custom.rs
index 3ecd6be..b320a57 100644
--- a/src/adapters/custom.rs
+++ b/src/adapters/custom.rs
@@ -232,16 +232,16 @@ mod test {
 
         let (a, d) = simple_adapt_info(&filepath, Box::new(File::open(&filepath)?));
         let mut r = adapter.adapt(a, &d)?;
-        let mut o = Vec::new();
-        r.read_to_end(&mut o)?;
+        let o = adapted_to_vec(r)?;
         assert_eq!(
             String::from_utf8(o)?,
-            "hello world
-this is just a test.
-
-1
-
-\u{c}"
+            "PREFIX:hello world
+PREFIX:this is just a test.
+PREFIX:
+PREFIX:1
+PREFIX:
+PREFIX:\u{c}
+"
         );
         Ok(())
     }
diff --git a/src/adapters/postproc.rs b/src/adapters/postproc.rs
index fa2d0ac..cbca91d 100644
--- a/src/adapters/postproc.rs
+++ b/src/adapters/postproc.rs
@@ -6,10 +6,39 @@ use anyhow::Result;
 
 use std::{cmp::min, io::Read};
 
-use crate::read_iter::{ReadIterBox, SingleReadIter};
+use crate::adapted_iter::{AdaptedFilesIterBox, SingleAdaptedFileAsIter};
 
 use super::{AdaptInfo, AdapterMeta, FileAdapter, GetMetadata};
 
+pub struct EnsureEndsWithNewline<R: Read> {
+    inner: R,
+    added_newline: bool,
+}
+impl<R: Read> EnsureEndsWithNewline<R> {
+    pub fn new(r: R) -> EnsureEndsWithNewline<R> {
+        EnsureEndsWithNewline {
+            inner: r,
+            added_newline: false,
+        }
+    }
+}
+impl<R: Read> Read for EnsureEndsWithNewline<R> {
+    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
+        match self.inner.read(buf) {
+            Ok(0) => {
+                if self.added_newline {
+                    Ok(0)
+                } else {
+                    buf[0] = b'\n';
+                    self.added_newline = true;
+                    Ok(1)
+                }
+            }
+            Ok(n) => Ok(n),
+            Err(e) => Err(e),
+        }
+    }
+}
 struct ByteReplacer<R>
 where
     R: Read,
@@ -99,15 +128,15 @@ impl FileAdapter for PostprocPrefix {
         &self,
         a: super::AdaptInfo<'a>,
         _detection_reason: &crate::matching::FileMatcher,
-    ) -> Result<ReadIterBox<'a>> {
-        let read = postproc_prefix(&a.line_prefix, a.inp)?;
+    ) -> Result<AdaptedFilesIterBox<'a>> {
+        let read = EnsureEndsWithNewline::new(postproc_prefix(&a.line_prefix, a.inp)?);
         // keep adapt info (filename etc) except replace inp
         let ai = AdaptInfo {
             inp: Box::new(read),
             postprocess: false,
             ..a
         };
-        Ok(Box::new(SingleReadIter::new(ai)))
+        Ok(Box::new(SingleAdaptedFileAsIter::new(ai)))
     }
 }
 
diff --git a/src/adapters/spawning.rs b/src/adapters/spawning.rs
index cf785ff..1de2e52 100644
--- a/src/adapters/spawning.rs
+++ b/src/adapters/spawning.rs
@@ -1,4 +1,4 @@
-use crate::read_iter::SingleReadIter;
+use crate::adapted_iter::SingleAdaptedFileAsIter;
 
 use super::*;
 use anyhow::*;
@@ -146,7 +146,7 @@ impl FileAdapter for SpawningFileAdapter {
         &self,
         ai: AdaptInfo<'a>,
         _detection_reason: &FileMatcher,
-    ) -> Result<ReadIterBox<'a>> {
+    ) -> Result<AdaptedFilesIterBox<'a>> {
         let AdaptInfo {
             filepath_hint,
             mut inp,
@@ -164,7 +164,7 @@ impl FileAdapter for SpawningFileAdapter {
             .with_context(|| format!("Could not set cmd arguments for {}", self.inner.get_exe()))?;
         debug!("executing {:?}", cmd);
         let output = pipe_output(&line_prefix, cmd, &mut inp, self.inner.get_exe(), "")?;
-        Ok(Box::new(SingleReadIter::new(AdaptInfo {
+        Ok(Box::new(SingleAdaptedFileAsIter::new(AdaptInfo {
             filepath_hint,
             inp: output,
             line_prefix,
diff --git a/src/adapters/zip.rs b/src/adapters/zip.rs
index 2c1398b..7a2d614 100644
--- a/src/adapters/zip.rs
+++ b/src/adapters/zip.rs
@@ -1,5 +1,5 @@
 use super::*;
-use crate::{print_bytes, read_iter::ReadIter};
+use crate::{adapted_iter::AdaptedFilesIter, print_bytes};
 use anyhow::*;
 use lazy_static::lazy_static;
 use log::*;
@@ -40,7 +40,7 @@ impl FileAdapter for ZipAdapter {
         &self,
         inp: AdaptInfo<'a>,
         _detection_reason: &FileMatcher,
-    ) -> Result<Box<dyn ReadIter + 'a>> {
+    ) -> Result<Box<dyn AdaptedFilesIter + 'a>> {
         Ok(Box::new(ZipAdaptIter { inp }))
     }
 }
@@ -48,7 +48,7 @@ impl FileAdapter for ZipAdapter {
 struct ZipAdaptIter<'a> {
     inp: AdaptInfo<'a>,
 }
-impl<'a> ReadIter for ZipAdaptIter<'a> {
+impl<'a> AdaptedFilesIter for ZipAdaptIter<'a> {
     fn next<'b>(&'b mut self) -> Option<AdaptInfo<'b>> {
         let line_prefix = &self.inp.line_prefix;
         let filepath_hint = &self.inp.filepath_hint;
@@ -115,14 +115,11 @@ mod test {
             &PathBuf::from("outer.zip"),
             Box::new(std::io::Cursor::new(zipfile)),
         );
-        let mut res = RecursingConcattyReader::concat(adapter.adapt(a, &d)?);
-
-        let mut buf = Vec::new();
-        res.read_to_end(&mut buf)?;
+        let buf = adapted_to_vec(adapter.adapt(a, &d)?)?;
 
         assert_eq!(
             String::from_utf8(buf)?,
-            "PREFIX:outer.txt:outer text file\n",
+            "PREFIX:outer.txt: outer text file\nPREFIX:inner.zip: inner.txt: inner text file\n",
         );
 
         Ok(())
diff --git a/src/lib.rs b/src/lib.rs
index 6956804..b7ea539 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,7 +1,7 @@
 #![warn(clippy::all)]
 #![feature(negative_impls)]
-#![feature(specialization)]
 
+pub mod adapted_iter;
 pub mod adapters;
 mod caching_writer;
 pub mod config;
@@ -9,7 +9,6 @@ pub mod matching;
 pub mod pipe;
 pub mod preproc;
 pub mod preproc_cache;
-pub mod read_iter;
 pub mod recurse;
 #[cfg(test)]
 pub mod test_utils;
diff --git a/src/recurse.rs b/src/recurse.rs
index 1c94fba..2c3418d 100644
--- a/src/recurse.rs
+++ b/src/recurse.rs
@@ -1,15 +1,15 @@
 use crate::preproc::rga_preproc;
-use crate::{adapters::*, read_iter::ReadIterBox};
+use crate::{adapted_iter::AdaptedFilesIterBox, adapters::*};
 
 use anyhow::*;
 use std::io::Read;
 
 pub struct RecursingConcattyReader<'a> {
-    inp: ReadIterBox<'a>,
+    inp: AdaptedFilesIterBox<'a>,
     cur: Option<ReadBox<'a>>,
 }
 impl<'a> RecursingConcattyReader<'a> {
-    pub fn concat(inp: ReadIterBox<'a>) -> Result<Box<dyn Read + 'a>> {
+    pub fn concat(inp: AdaptedFilesIterBox<'a>) -> Result<Box<dyn Read + 'a>> {
         let mut r = RecursingConcattyReader { inp, cur: None };
         r.ascend()?;
         Ok(Box::new(r))
@@ -20,7 +20,7 @@ impl<'a> RecursingConcattyReader<'a> {
         // we only need to access the inp: ReadIter when the inner reader is done, so this should be safe
         let ai = unsafe {
             // would love to make this safe, but how? something like OwnedRef<inp, cur>
-            (*(inp as *mut ReadIterBox<'a>)).next()
+            (*(inp as *mut AdaptedFilesIterBox<'a>)).next()
         };
         self.cur = match ai {
             Some(ai) => Some(rga_preproc(ai)?),
diff --git a/src/test_utils.rs b/src/test_utils.rs
index 5bbaebc..3ab4cc2 100644
--- a/src/test_utils.rs
+++ b/src/test_utils.rs
@@ -1,8 +1,11 @@
 use crate::{
+    adapted_iter::AdaptedFilesIterBox,
     adapters::{AdaptInfo, ReadBox},
     config::RgaConfig,
     matching::{FastFileMatcher, FileMatcher},
+    recurse::RecursingConcattyReader,
 };
+use anyhow::Result;
 use std::path::{Path, PathBuf};
 
 pub fn test_data_dir() -> PathBuf {
@@ -28,3 +31,11 @@ pub fn simple_adapt_info<'a>(filepath: &Path, inp: ReadBox<'a>) -> (AdaptInfo<'a
         .into(),
     )
 }
+
+pub fn adapted_to_vec(adapted: AdaptedFilesIterBox<'_>) -> Result<Vec<u8>> {
+    let mut res = RecursingConcattyReader::concat(adapted)?;
+
+    let mut buf = Vec::new();
+    res.read_to_end(&mut buf)?;
+    Ok(buf)
+}