diff --git a/src/bng/score.rs b/src/bng/score.rs
index 5e5e601..de6de55 100644
--- a/src/bng/score.rs
+++ b/src/bng/score.rs
@@ -1,4 +1,7 @@
-use std::num::{NonZeroU16, NonZeroU8};
+use std::{
+    error::Error,
+    num::{NonZeroU16, NonZeroU8},
+};
 
 use amplify::From;
 use anyhow::Context;
@@ -8,8 +11,8 @@ use derived_deref::Deref;
 use lex::lexer::flat_atom_parser;
 use nom::{
     branch::alt,
-    character::complete::char,
-    combinator::eof,
+    character::{complete::char, streaming::one_of},
+    combinator::{all_consuming, eof},
     multi::many0,
     sequence::{preceded, terminated},
 };
@@ -34,12 +37,29 @@ pub struct Atoms(Vec<Atom>);
 
 #[derive(Debug, Error)]
 enum AtomsSerializeError {
-    #[error("error while parsing with nom")]
+    #[error("sheet parsing error: {0}")]
     Parsing(String),
-    #[error("error while inflating flat atoms")]
+    #[error("sheet semantics: {0}")]
     Inflation(#[from] InflateError),
 }
 
+fn nom_err_message(e: nom::Err<nom::error::Error<&str>>) -> String {
+    match e {
+        nom::Err::Incomplete(needed) => todo!(),
+        nom::Err::Error(e) => format!(
+            "got error code {code:#?} at character n°{charn} (after \"{before}\")",
+            code = e.code,
+            charn = e.input.len() + 1,
+            before = &e.input[e.input.len()
+                - option_env!("SHEET_BACKTRACE")
+                    .and_then(|s| s.parse().ok())
+                    .unwrap_or(10usize)
+                + 1..]
+        ),
+        nom::Err::Failure(e) => todo!(),
+    }
+}
+
 impl<'de> Deserialize<'de> for Atoms {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -104,14 +124,11 @@ impl<'de> Deserialize<'de> for Atoms {
         const FIELDS: &[&str] = &["notes", "sheet"];
         let NotesSheet { notes, sheet } =
             deserializer.deserialize_struct("NotesSheet", FIELDS, NotesSheetVisitor)?;
-        let x = terminated(
-            many0(preceded(
-                many0(alt((char('\t'), char(' '), char('\n'), char('\r')))),
-                flat_atom_parser(&notes),
-            )),
-            eof,
-        )(&sheet)
-        .map_err(|e| e.to_string())
+        let x = all_consuming(terminated(
+            many0(preceded(many0(one_of(" \t\r")), flat_atom_parser(&notes))),
+            many0(alt((char('\t'), char(' '), char('\n'), char('\r')))),
+        ))(dbg!(&sheet))
+        .map_err(nom_err_message)
         .map_err(AtomsSerializeError::Parsing)
         .map_err(de::Error::custom)
         .and_then(|(_, v)| {
diff --git a/src/main.rs b/src/main.rs
index 8d4b51c..5a0fccc 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,6 @@
 use std::collections::HashMap;
 
+use anyhow::Error;
 use bng::{BngFile, Channel, Expression, Instrument};
 /// TODO: remove clap, use only a file or standard in
 use clap::Parser;
@@ -9,7 +10,7 @@ use fasteval::Compiler;
 mod bng;
 mod cli;
 
-fn main() -> Result<(), serde_yml::Error> {
+fn main() -> Result<(), Error> {
     // println!("{}", option_env!("TEST").unwrap_or("ok"));
     let args = Cli::parse();
     // #[cfg(debug_assertions)]