diff --git a/src/cmd/sources.rs b/src/cmd/sources.rs
index 45413aed..f32d13b3 100644
--- a/src/cmd/sources.rs
+++ b/src/cmd/sources.rs
@@ -11,6 +11,7 @@ use indexmap::{IndexMap, IndexSet};
 use serde_json;
 use tokio::runtime::Runtime;
 
+use crate::config::Validate;
 use crate::error::*;
 use crate::sess::{Session, SessionIo};
 use crate::src::SourceGroup;
@@ -148,6 +149,8 @@ pub fn run(sess: &Session, matches: &ArgMatches) -> Result<()> {
             });
     }
 
+    srcs = srcs.validate("", false, &sess.suppress_warnings)?;
+
     let mut target_defines: IndexMap<String, Option<String>> = IndexMap::new();
     target_defines.extend(
         targets
diff --git a/src/config.rs b/src/config.rs
index e134e94b..cd474959 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -489,7 +489,28 @@ impl Validate for PartialManifest {
             export_include_dirs: exp_inc_dirs
                 .iter()
                 .filter_map(|path| match env_path_from_string(path.to_string()) {
-                    Ok(parsed_path) => Some(Ok(parsed_path)),
+                    Ok(parsed_path) => {
+                        if (parsed_path.exists() && parsed_path.is_dir())
+                            || suppress_warnings.contains("E31")
+                            || pre_output
+                        {
+                            if !(suppress_warnings.contains("W31")
+                                || pre_output
+                                || parsed_path.exists() && parsed_path.is_dir())
+                            {
+                                warnln!(
+                                    "[W31] Include directory {} doesn't exist.",
+                                    &parsed_path.display()
+                                );
+                            }
+                            Some(Ok(parsed_path))
+                        } else {
+                            Some(Err(Error::new(format!(
+                                "[E31] Include directory {} doesn't exist",
+                                &parsed_path.display()
+                            ))))
+                        }
+                    }
                     Err(cause) => {
                         if suppress_warnings.contains("E30") {
                             if !suppress_warnings.contains("W30") {
diff --git a/src/sess.rs b/src/sess.rs
index b88f1db6..fa6fb29e 100644
--- a/src/sess.rs
+++ b/src/sess.rs
@@ -30,8 +30,7 @@ use tokio::sync::Semaphore;
 use typed_arena::Arena;
 
 use crate::cli::read_manifest;
-//use crate::config::Validate;
-use crate::config::{self, Config, Manifest};
+use crate::config::{self, Config, Manifest, PartialManifest};
 use crate::error::*;
 use crate::git::Git;
 use crate::src::SourceGroup;
@@ -1160,15 +1159,22 @@ impl<'io, 'sess: 'io, 'ctx: 'sess> SessionIo<'sess, 'ctx> {
                     .join(format!("{}_manifest.yml", dep.name))
                     .exists()
                 {
-                    match read_manifest(
-                        &self
-                            .sess
+                    let file = std::fs::File::open(
+                        self.sess
                             .root
                             .join(".bender")
                             .join("tmp")
                             .join(format!("{}_manifest.yml", dep.name)),
-                        &self.sess.suppress_warnings,
-                    ) {
+                    )
+                    .map_err(|cause| {
+                        Error::chain(format!("Cannot open manifest {:?}.", path), cause)
+                    })?;
+                    let partial: PartialManifest =
+                        serde_yaml_ng::from_reader(file).map_err(|cause| {
+                            Error::chain(format!("Syntax error in manifest {:?}.", path), cause)
+                        })?;
+
+                    match partial.validate_ignore_sources("", true, &self.sess.suppress_warnings) {
                         Ok(m) => {
                             if dep.name != m.package.name
                                 && !self.sess.suppress_warnings.contains("W11")
@@ -1181,6 +1187,26 @@ impl<'io, 'sess: 'io, 'ctx: 'sess> SessionIo<'sess, 'ctx> {
                         Err(e) => Err(e),
                     }
                 } else {
+                    if !(self.sess.suppress_warnings.contains("E32")
+                        && self.sess.suppress_warnings.contains("W32"))
+                    {
+                        if let DepSrc::Path(ref path) = dep.source {
+                            if !path.exists() {
+                                if self.sess.suppress_warnings.contains("E32") {
+                                    warnln!(
+                                        "[W32] Path {:?} for dependency {:?} does not exist.",
+                                        path,
+                                        dep.name
+                                    );
+                                } else {
+                                    return Err(Error::new(format!(
+                                        "[E32] Path {:?} for dependency {:?} does not exist.",
+                                        path, dep.name
+                                    )));
+                                }
+                            }
+                        }
+                    }
                     if !self.sess.suppress_warnings.contains("W12") {
                         warnln!(
                             "[W12] Manifest not found for {:?} at {:?}",
diff --git a/src/src.rs b/src/src.rs
index 45f8ad21..ce5eeb05 100644
--- a/src/src.rs
+++ b/src/src.rs
@@ -58,6 +58,23 @@ impl<'ctx> Validate for SourceGroup<'ctx> {
                 .into_iter()
                 .map(|f| f.validate(package_name, pre_output, suppress_warnings))
                 .collect::<Result<Vec<_>, Error>>()?,
+            include_dirs: self
+                .include_dirs
+                .into_iter()
+                .map(|p| {
+                    if (p.exists() && p.is_dir()) || suppress_warnings.contains("E31") {
+                        if !(suppress_warnings.contains("W31") || p.exists() && p.is_dir()) {
+                            warnln!("[W31] Include directory {} doesn't exist.", p.display());
+                        }
+                        Ok(p)
+                    } else {
+                        Err(Error::new(format!(
+                            "[E31] Include directory {} doesn't exist.",
+                            p.display()
+                        )))
+                    }
+                })
+                .collect::<Result<IndexSet<_>, Error>>()?,
             ..self
         })
     }