diff --git a/mers/src/main.rs b/mers/src/main.rs
index f22e4c0..147fe17 100755
--- a/mers/src/main.rs
+++ b/mers/src/main.rs
@@ -69,17 +69,14 @@ fn main() {
     });
     let (mut info_parsed, mut info_run, mut info_check) = config.infos();
     let mut source = match args.command {
-        Command::Run { file } => {
-            let str = match fs::read_to_string(&file) {
-                Ok(s) => s,
-                Err(e) => {
-                    eprintln!("Can't read file {file:?}: {e}");
-                    exit(10);
-                }
-            };
-            Source::new(str)
-        }
-        Command::Exec { source } => Source::new(source),
+        Command::Run { file } => match Source::new_from_file(PathBuf::from(&file)) {
+            Ok(s) => s,
+            Err(e) => {
+                eprintln!("Can't read file {file:?}: {e}");
+                exit(10);
+            }
+        },
+        Command::Exec { source } => Source::new_from_string(source),
     };
     let parsed = match parse(&mut source) {
         Ok(v) => v,
diff --git a/mers_lib/src/errors/mod.rs b/mers_lib/src/errors/mod.rs
index 85f8e33..fe7516a 100644
--- a/mers_lib/src/errors/mod.rs
+++ b/mers_lib/src/errors/mod.rs
@@ -1,4 +1,4 @@
-use std::fmt::Display;
+use std::fmt::{Debug, Display};
 
 use colored::Colorize;
 use line_span::LineSpans;
@@ -35,7 +35,6 @@ impl SourceRange {
         self.end
     }
 }
-#[derive(Clone, Debug)]
 pub struct CheckError(Vec<CheckErrorComponent>);
 #[allow(non_upper_case_globals)]
 pub mod error_colors {
@@ -65,10 +64,10 @@ pub mod error_colors {
     pub const AssignTo: Color = InitTo;
     pub const AssignTargetNonReference: Color = Color::BrightYellow;
 }
-#[derive(Clone, Debug)]
 enum CheckErrorComponent {
     Message(String),
     Error(CheckError),
+    ErrorWithSrc(CheckErrorWithSrc),
     Source(Vec<(SourceRange, Option<colored::Color>)>),
 }
 #[derive(Clone)]
@@ -86,6 +85,12 @@ pub struct CheckErrorDisplay<'a> {
     pub show_comments: bool,
 }
 #[cfg(feature = "parse")]
+pub struct CheckErrorWithSrc {
+    e: CheckError,
+    src: Source,
+    pub show_comments: bool,
+}
+#[cfg(feature = "parse")]
 impl<'a> CheckErrorDisplay<'a> {
     pub fn show_comments(mut self, show_comments: bool) -> Self {
         self.show_comments = show_comments;
@@ -93,6 +98,13 @@ impl<'a> CheckErrorDisplay<'a> {
     }
 }
 #[cfg(feature = "parse")]
+impl CheckErrorWithSrc {
+    pub fn show_comments(mut self, show_comments: bool) -> Self {
+        self.show_comments = show_comments;
+        self
+    }
+}
+#[cfg(feature = "parse")]
 impl Display for CheckErrorDisplay<'_> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         self.e.human_readable(
@@ -107,6 +119,21 @@ impl Display for CheckErrorDisplay<'_> {
         )
     }
 }
+#[cfg(feature = "parse")]
+impl Display for CheckErrorWithSrc {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.e.human_readable(
+            f,
+            Some(&self.src),
+            &CheckErrorHRConfig {
+                indent_start: String::new(),
+                indent_default: String::new(),
+                indent_end: String::new(),
+                show_comments: self.show_comments,
+            },
+        )
+    }
+}
 impl CheckError {
     pub fn new() -> Self {
         CheckError(vec![])
@@ -121,6 +148,13 @@ impl CheckError {
     pub(crate) fn err(self, e: Self) -> Self {
         self.add(CheckErrorComponent::Error(e))
     }
+    pub(crate) fn err_with_src(self, e: CheckError, src: Source) -> Self {
+        self.add(CheckErrorComponent::ErrorWithSrc(CheckErrorWithSrc {
+            e,
+            src,
+            show_comments: true,
+        }))
+    }
     pub(crate) fn src(self, s: Vec<(SourceRange, Option<colored::Color>)>) -> Self {
         self.add(CheckErrorComponent::Source(s))
     }
@@ -148,6 +182,8 @@ impl CheckError {
         src: Option<&Source>,
         cfg: &CheckErrorHRConfig,
     ) -> std::fmt::Result {
+        use crate::parsing::SourceFrom;
+
         let len = self.0.len();
         for (i, component) in self.0.iter().enumerate() {
             macro_rules! indent {
@@ -170,6 +206,14 @@ impl CheckError {
                     cfg.indent_end.push_str("└");
                     err.human_readable(f, src, &cfg)?;
                 }
+                CheckErrorComponent::ErrorWithSrc(err) => {
+                    let mut cfg = cfg.clone();
+                    cfg.indent_start.push_str(&"│".bright_yellow().to_string());
+                    cfg.indent_default
+                        .push_str(&"│".bright_yellow().to_string());
+                    cfg.indent_end.push_str(&"└".bright_yellow().to_string());
+                    err.e.human_readable(f, Some(&err.src), &cfg)?;
+                }
                 CheckErrorComponent::Source(highlights) => {
                     if let Some(src) = src {
                         let start = highlights.iter().map(|v| v.0.start.pos()).min();
@@ -218,21 +262,27 @@ impl CheckError {
                                     }
                                 })
                                 .count();
+                            let src_from = match src.src_from() {
+                                SourceFrom::File(path) => format!(" [{}]", path.to_string_lossy()),
+                                SourceFrom::Unspecified => String::with_capacity(0),
+                            };
                             if first_line_nr == last_line_nr {
                                 writeln!(
                                     f,
-                                    "{}Line {first_line_nr} ({}..{})",
+                                    "{}Line {first_line_nr} ({}..{}){}",
                                     indent!(),
                                     start_with_comments + 1 - first_line_start,
                                     end_with_comments - last_line_start,
+                                    src_from,
                                 )?;
                             } else {
                                 writeln!(
                                     f,
-                                    "{}Lines {first_line_nr}-{last_line_nr} ({}..{})",
+                                    "{}Lines {first_line_nr}-{last_line_nr} ({}..{}){}",
                                     indent!(),
                                     start_with_comments + 1 - first_line_start,
                                     end_with_comments - last_line_start,
+                                    src_from,
                                 )?;
                             }
                             let lines = if cfg.show_comments {
@@ -306,3 +356,13 @@ impl From<String> for CheckError {
         Self::new().msg(value)
     }
 }
+impl Debug for CheckError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{self}")
+    }
+}
+impl Display for CheckError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.display_no_src())
+    }
+}
diff --git a/mers_lib/src/parsing/mod.rs b/mers_lib/src/parsing/mod.rs
index ce05167..b76995f 100755
--- a/mers_lib/src/parsing/mod.rs
+++ b/mers_lib/src/parsing/mod.rs
@@ -1,4 +1,4 @@
-use std::sync::Arc;
+use std::{fmt::Debug, path::PathBuf, sync::Arc};
 
 use crate::{
     errors::{CheckError, SourcePos},
@@ -19,6 +19,7 @@ pub fn parse(src: &mut Source) -> Result<Box<dyn program::parsed::MersStatement>
 }
 
 pub struct Source {
+    src_from: SourceFrom,
     src_raw_len: usize,
     src_og: String,
     src: String,
@@ -27,8 +28,38 @@ pub struct Source {
     i: usize,
     sections: Vec<SectionMarker>,
 }
+impl Clone for Source {
+    fn clone(&self) -> Self {
+        Self {
+            src_from: self.src_from.clone(),
+            src_raw_len: self.src_raw_len,
+            src_og: self.src_og.clone(),
+            src: self.src.clone(),
+            comments: self.comments.clone(),
+            i: self.i,
+            sections: vec![],
+        }
+    }
+}
+impl Debug for Source {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Src: {:?}", self.src_from)
+    }
+}
+#[derive(Clone, Debug)]
+pub enum SourceFrom {
+    File(PathBuf),
+    Unspecified,
+}
 impl Source {
-    pub fn new(source: String) -> Self {
+    pub fn new_from_file(path: PathBuf) -> std::io::Result<Self> {
+        let content = std::fs::read_to_string(&path)?;
+        Ok(Self::new(SourceFrom::File(path), content))
+    }
+    pub fn new_from_string(source: String) -> Self {
+        Self::new(SourceFrom::Unspecified, source)
+    }
+    pub fn new(src_from: SourceFrom, source: String) -> Self {
         let mut src = String::with_capacity(source.len());
         let mut comment = (0, String::new());
         let mut comments = Vec::new();
@@ -88,6 +119,7 @@ impl Source {
             }
         }
         Self {
+            src_from,
             src_raw_len: source.len(),
             src_og: source,
             src,
@@ -228,6 +260,10 @@ impl Source {
         o
     }
 
+    pub fn src_from(&self) -> &SourceFrom {
+        &self.src_from
+    }
+
     pub fn pos_in_og(&self, mut pos: usize, inclusive: bool) -> usize {
         for (start, comment) in &self.comments {
             if *start < pos || (inclusive && *start == pos) {
diff --git a/mers_lib/src/parsing/statements.rs b/mers_lib/src/parsing/statements.rs
index df5bb43..8ad4a71 100755
--- a/mers_lib/src/parsing/statements.rs
+++ b/mers_lib/src/parsing/statements.rs
@@ -1,4 +1,4 @@
-use std::fs;
+use std::path::PathBuf;
 
 use super::{Source, SourcePos};
 use crate::{
@@ -154,13 +154,21 @@ pub fn parse_no_chain(
                     src.skip_whitespace();
                     let string_in_src = src.get_pos();
                     if src.next_char() == Some('"') {
-                        let s = parse_string(src, string_in_src)?;
-                        match fs::read_to_string(&s) {
-                            Ok(s) => {
+                        let file_path = parse_string(src, string_in_src)?;
+                        match Source::new_from_file(PathBuf::from(&file_path)) {
+                            Ok(mut inner_src) => {
                                 return Ok(Some(Box::new(
                                     program::parsed::include_mers::IncludeMers {
                                         pos_in_src: (pos_in_src, src.get_pos()).into(),
-                                        include: super::parse(&mut Source::new(s))?,
+                                        include: match super::parse(&mut inner_src) {
+                                            Ok(v) => v,
+                                            Err(e) => {
+                                                return Err(
+                                                    CheckError::new().err_with_src(e, inner_src)
+                                                )
+                                            }
+                                        },
+                                        inner_src,
                                     },
                                 )));
                             }
@@ -173,7 +181,7 @@ pub fn parse_no_chain(
                                             Some(error_colors::HashIncludeCantLoadFile),
                                         ),
                                     ])
-                                    .msg(format!("Can't load file '{s}': {e}")));
+                                    .msg(format!("Can't load file '{file_path}': {e}")));
                             }
                         }
                     } else {
diff --git a/mers_lib/src/program/parsed/chain.rs b/mers_lib/src/program/parsed/chain.rs
index a62832b..cdac4d0 100755
--- a/mers_lib/src/program/parsed/chain.rs
+++ b/mers_lib/src/program/parsed/chain.rs
@@ -24,6 +24,7 @@ impl MersStatement for Chain {
             pos_in_src: self.pos_in_src,
             first: self.first.compile(info, comp)?,
             chained: self.chained.compile(info, comp)?,
+            as_part_of_include: None,
         }))
     }
     fn source_range(&self) -> SourceRange {
diff --git a/mers_lib/src/program/parsed/include_mers.rs b/mers_lib/src/program/parsed/include_mers.rs
index 85da98f..16dca44 100644
--- a/mers_lib/src/program/parsed/include_mers.rs
+++ b/mers_lib/src/program/parsed/include_mers.rs
@@ -6,6 +6,7 @@ use crate::{
     data::{self, Data},
     errors::{error_colors, CheckError, SourceRange},
     info::{self, Local},
+    parsing::Source,
     program::{self},
 };
 
@@ -15,6 +16,7 @@ use super::{CompInfo, MersStatement};
 pub struct IncludeMers {
     pub pos_in_src: SourceRange,
     pub include: Box<dyn MersStatement>,
+    pub inner_src: Source,
 }
 impl MersStatement for IncludeMers {
     fn has_scope(&self) -> bool {
@@ -25,15 +27,23 @@ impl MersStatement for IncludeMers {
         info: &mut info::Info<super::Local>,
         comp: CompInfo,
     ) -> Result<Box<dyn program::run::MersStatement>, CheckError> {
-        let compiled: Arc<Box<dyn crate::program::run::MersStatement>> = match self.include.compile(info, comp) {
-            Ok(v) => Arc::new(v),
-            Err(e) => {
-                return Err(CheckError::new()
-                    .src(vec![(self.pos_in_src, Some(error_colors::HashIncludeErrorInIncludedFile))])
-                    .msg("Error in inner mers statement! (note: inner errors may refer to a different file)".color(error_colors::HashIncludeErrorInIncludedFile).to_string())
-                .err(e))
-            }
-        };
+        let compiled: Arc<Box<dyn crate::program::run::MersStatement>> =
+            match self.include.compile(info, comp) {
+                Ok(v) => Arc::new(v),
+                Err(e) => {
+                    return Err(CheckError::new()
+                        .src(vec![(
+                            self.pos_in_src,
+                            Some(error_colors::HashIncludeErrorInIncludedFile),
+                        )])
+                        .msg(
+                            "Error in #include! (note: inner errors may refer to a different file)"
+                                .color(error_colors::HashIncludeErrorInIncludedFile)
+                                .to_string(),
+                        )
+                        .err_with_src(e, self.inner_src.clone()))
+                }
+            };
         let compiled2 = Arc::clone(&compiled);
         Ok(Box::new(program::run::chain::Chain {
             pos_in_src: self.pos_in_src,
@@ -50,6 +60,7 @@ impl MersStatement for IncludeMers {
                     run: Arc::new(move |_, i| compiled2.run(&mut i.duplicate())),
                 },
             }),
+            as_part_of_include: Some(self.inner_src.clone()),
         }))
     }
     fn source_range(&self) -> SourceRange {
diff --git a/mers_lib/src/program/run/assign_to.rs b/mers_lib/src/program/run/assign_to.rs
index 3aa8de8..e52bf36 100755
--- a/mers_lib/src/program/run/assign_to.rs
+++ b/mers_lib/src/program/run/assign_to.rs
@@ -31,8 +31,8 @@ impl MersStatement for AssignTo {
                 return Err(CheckError::new()
                     .src(vec![
                         (self.pos_in_src, None),
-                        (self.target.source_range(), Some(error_colors::InitFrom)),
-                        (self.source.source_range(), Some(error_colors::InitTo)),
+                        (self.target.source_range(), Some(error_colors::InitTo)),
+                        (self.source.source_range(), Some(error_colors::InitFrom)),
                     ])
                     .msg(format!("Cannot initialize:"))
                     .err(e))
diff --git a/mers_lib/src/program/run/chain.rs b/mers_lib/src/program/run/chain.rs
index 397d952..a67fdd0 100755
--- a/mers_lib/src/program/run/chain.rs
+++ b/mers_lib/src/program/run/chain.rs
@@ -5,6 +5,7 @@ use colored::Colorize;
 use crate::{
     data::{Data, Type},
     errors::{error_colors, CheckError, SourceRange},
+    parsing::Source,
 };
 
 use super::MersStatement;
@@ -14,6 +15,7 @@ pub struct Chain {
     pub pos_in_src: SourceRange,
     pub first: Box<dyn MersStatement>,
     pub chained: Box<dyn MersStatement>,
+    pub as_part_of_include: Option<Source>,
 }
 impl MersStatement for Chain {
     fn check_custom(
@@ -35,21 +37,35 @@ impl MersStatement for Chain {
                 match (func.0)(&arg) {
                     Ok(t) => o.add(Arc::new(t)),
                     Err(e) => {
-                        return Err(CheckError::new()
-                            .src(vec![
-                                (self.pos_in_src, None),
-                                (
-                                    self.first.source_range(),
-                                    Some(error_colors::FunctionArgument),
-                                ),
-                                (self.chained.source_range(), Some(error_colors::Function)),
-                            ])
-                            .msg(format!(
-                                "Can't call {} with an argument of type {}:",
-                                "this function".color(error_colors::Function),
-                                arg.to_string().color(error_colors::FunctionArgument)
-                            ))
-                            .err(e))
+                        return Err(if let Some(inner_src) = &self.as_part_of_include {
+                            CheckError::new()
+                                .src(vec![(
+                                    self.pos_in_src,
+                                    Some(error_colors::HashIncludeErrorInIncludedFile),
+                                )])
+                                .msg(
+                                    "Error in #include:"
+                                        .color(error_colors::HashIncludeErrorInIncludedFile)
+                                        .to_string(),
+                                )
+                                .err_with_src(e, inner_src.clone())
+                        } else {
+                            CheckError::new()
+                                .src(vec![
+                                    (self.pos_in_src, None),
+                                    (
+                                        self.first.source_range(),
+                                        Some(error_colors::FunctionArgument),
+                                    ),
+                                    (self.chained.source_range(), Some(error_colors::Function)),
+                                ])
+                                .msg(format!(
+                                    "Can't call {} with an argument of type {}:",
+                                    "this function".color(error_colors::Function),
+                                    arg.to_string().color(error_colors::FunctionArgument)
+                                ))
+                                .err(e)
+                        })
                     }
                 }
             } else {
diff --git a/mers_lib/src/program/run/tuple.rs b/mers_lib/src/program/run/tuple.rs
index f082072..6e0a8f9 100755
--- a/mers_lib/src/program/run/tuple.rs
+++ b/mers_lib/src/program/run/tuple.rs
@@ -45,7 +45,20 @@ impl MersStatement for Tuple {
                             ).into());
                     }
                 } else {
-                    return Err(format!("can't init a {} with a value of type {}, which is part of {} - only tuples can be assigned to tuples", "tuple".color(error_colors::InitTo), t.to_string().color(error_colors::InitFrom), init_to.to_string().color(error_colors::InitFrom)).into());
+                    return Err(format!(
+                        "can't init a {} with type {}{} - only tuples can be assigned to tuples",
+                        "tuple".color(error_colors::InitTo),
+                        t.to_string().color(error_colors::InitFrom),
+                        if print_is_part_of {
+                            format!(
+                                ", which is part of {}",
+                                init_to.to_string().color(error_colors::InitFrom)
+                            )
+                        } else {
+                            format!("")
+                        }
+                    )
+                    .into());
                 }
             }
             Some(vec)