diff --git a/src/build.rs b/src/build.rs
index 1586f9d..c03d845 100644
--- a/src/build.rs
+++ b/src/build.rs
@@ -1155,6 +1155,74 @@ fn compute_file_hash(path: &str) -> Option<blake3::Hash> {
     }
 }
 
+fn find_dependency_cycle(modules: &Vec<(&String, &Module)>) -> Vec<String> {
+    let mut visited: AHashSet<String> = AHashSet::new();
+    let mut stack: Vec<String> = vec![];
+
+    // we want to sort the module names so that we always return the same
+    // dependency cycle (there can be more than one)
+    let mut module_names = modules
+        .iter()
+        .map(|(name, _)| name.to_string())
+        .collect::<Vec<String>>();
+
+    module_names.sort_by(|a, b| a.cmp(b));
+    for module_name in module_names {
+        if find_dependency_cycle_helper(&module_name, &modules, &mut visited, &mut stack) {
+            return stack;
+        }
+        visited.clear();
+        stack.clear();
+    }
+    stack
+}
+
+fn find_dependency_cycle_helper(
+    module_name: &String,
+    modules: &Vec<(&String, &Module)>,
+    visited: &mut AHashSet<String>,
+    stack: &mut Vec<String>,
+) -> bool {
+    if let Some(module) = modules
+        .iter()
+        .find(|(name, _)| *name == module_name)
+        .map(|(_, module)| module)
+    {
+        visited.insert(module_name.to_string());
+        // if the module is a mlmap (namespace), we don't want to show this in the path
+        // because the namespace is not a module the user created, so only add source files
+        // to the stack
+        if let SourceType::SourceFile(_) = module.source_type {
+            stack.push(module_name.to_string())
+        }
+        for dep in &module.deps {
+            if !visited.contains(dep) {
+                if find_dependency_cycle_helper(dep, modules, visited, stack) {
+                    return true;
+                }
+            } else if stack.contains(dep) {
+                stack.push(dep.to_string());
+                return true;
+            }
+        }
+        // because we only pushed source files to the stack, we also only need to
+        // pop these from the stack if we don't find a dependency cycle
+        if let SourceType::SourceFile(_) = module.source_type {
+            let _ = stack.pop();
+        }
+        return false;
+    }
+    false
+}
+
+fn format_dependency_cycle(cycle: &Vec<String>) -> String {
+    cycle
+        .iter()
+        .map(|s| helpers::format_namespaced_module_name(s))
+        .collect::<Vec<String>>()
+        .join(" -> ")
+}
+
 pub fn build(filter: &Option<regex::Regex>, path: &str, no_timing: bool) -> Result<BuildState, ()> {
     let timing_total = Instant::now();
     let project_root = helpers::get_abs_path(path);
@@ -1322,8 +1390,7 @@ pub fn build(filter: &Option<regex::Regex>, path: &str, no_timing: bool) -> Resu
     // we get this by traversing from the dirty modules to all the modules that
     // are dependent on them
     let mut compile_universe = dirty_modules.clone();
-
-    let mut current_step_modules = dirty_modules.clone();
+    let mut current_step_modules = compile_universe.clone();
     loop {
         let mut dependents: AHashSet<String> = AHashSet::new();
         for dirty_module in current_step_modules.iter() {
@@ -1334,7 +1401,7 @@ pub fn build(filter: &Option<regex::Regex>, path: &str, no_timing: bool) -> Resu
             .map(|s| s.to_string())
             .collect::<AHashSet<String>>();
 
-        compile_universe.extend(current_step_modules.clone());
+        compile_universe.extend(current_step_modules.to_owned());
         if current_step_modules.is_empty() {
             break;
         }
@@ -1371,8 +1438,9 @@ pub fn build(filter: &Option<regex::Regex>, path: &str, no_timing: bool) -> Resu
             loop_count,
         );
 
-        in_progress_modules
-            .clone()
+        let current_in_progres_modules = in_progress_modules.clone();
+
+        current_in_progres_modules
             .par_iter()
             .map(|module_name| {
                 let module = build_state.get_module(module_name).unwrap();
@@ -1602,8 +1670,18 @@ pub fn build(filter: &Option<regex::Regex>, path: &str, no_timing: bool) -> Resu
             break;
         }
         if in_progress_modules.len() == 0 {
-            // we probably want to find the cycle(s), and give a helpful error message here
-            compile_errors.push_str("Can't continue... Dependency cycle\n")
+            // find the dependency cycle
+            let cycle = find_dependency_cycle(
+                &compile_universe
+                    .iter()
+                    .map(|s| (s, build_state.get_module(s).unwrap()))
+                    .collect::<Vec<(&String, &Module)>>(),
+            );
+            compile_errors.push_str(&format!(
+                "\n{}\n{}\n",
+                style("Can't continue... Found a circular dependency in your code:").red(),
+                format_dependency_cycle(&cycle)
+            ))
         }
         if compile_errors.len() > 0 {
             break;
diff --git a/src/helpers.rs b/src/helpers.rs
index dc0d8a1..851e7d6 100644
--- a/src/helpers.rs
+++ b/src/helpers.rs
@@ -314,3 +314,16 @@ pub fn get_extension(path: &str) -> String {
         .expect("Could not get extension 2")
         .to_string();
 }
+
+pub fn format_namespaced_module_name(module_name: &str) -> String {
+    // from ModuleName-Namespace to Namespace.ModuleName
+    // also format ModuleName-@Namespace to Namespace.ModuleName
+    let mut split = module_name.split("-");
+    let module_name = split.next().unwrap();
+    let namespace = split.next();
+    let namespace = namespace.map(|ns| ns.trim_start_matches("@"));
+    return match namespace {
+        None => module_name.to_string(),
+        Some(ns) => ns.to_string() + "." + module_name,
+    };
+}
diff --git a/testrepo/packages/dep01/bsconfig.json b/testrepo/packages/dep01/bsconfig.json
index 7f305a0..106a46f 100644
--- a/testrepo/packages/dep01/bsconfig.json
+++ b/testrepo/packages/dep01/bsconfig.json
@@ -9,7 +9,5 @@
     "in-source": true
   },
   "suffix": ".bs.js",
-  "bs-dependencies": [
-          "@testrepo/dep02"
-  ]
+  "bs-dependencies": ["@testrepo/dep02"]
 }
diff --git a/testrepo/packages/dep01/src/Dep01.mjs b/testrepo/packages/dep01/src/Dep01.mjs
index 3fac616..ea2a8df 100644
--- a/testrepo/packages/dep01/src/Dep01.mjs
+++ b/testrepo/packages/dep01/src/Dep01.mjs
@@ -10,4 +10,4 @@ function log(param) {
 export {
   log ,
 }
-/* No side effect */
+/* Dep02 Not a pure module */
diff --git a/testrepo/packages/dep02/bsconfig.json b/testrepo/packages/dep02/bsconfig.json
index fc120a1..0355169 100644
--- a/testrepo/packages/dep02/bsconfig.json
+++ b/testrepo/packages/dep02/bsconfig.json
@@ -9,5 +9,5 @@
     "in-source": true
   },
   "suffix": ".bs.js",
-  "bs-dependencies": []
+  "bs-dependencies": ["@testrepo/new-namespace"]
 }
diff --git a/testrepo/packages/dep02/src/Dep02.mjs b/testrepo/packages/dep02/src/Dep02.mjs
index fed28ac..856730e 100644
--- a/testrepo/packages/dep02/src/Dep02.mjs
+++ b/testrepo/packages/dep02/src/Dep02.mjs
@@ -1,6 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 import * as $$Array from "./Array.mjs";
+import * as NS_alias$$atNewNamespace from "@testrepo/new-namespace/src/NS_alias.mjs";
 
 function log(param) {
   $$Array.forEach([
@@ -11,7 +12,9 @@ function log(param) {
         }));
 }
 
+console.log(NS_alias$$atNewNamespace.hello_world(undefined));
+
 export {
   log ,
 }
-/* No side effect */
+/*  Not a pure module */
diff --git a/testrepo/packages/dep02/src/Dep02.res b/testrepo/packages/dep02/src/Dep02.res
index 8e2c651..e832615 100644
--- a/testrepo/packages/dep02/src/Dep02.res
+++ b/testrepo/packages/dep02/src/Dep02.res
@@ -1,2 +1,3 @@
-open Array;
+open Array
 let log = () => ["a", "b"]->forEach(Js.log)
+Js.log(NS.Alias.hello_world())
diff --git a/testrepo/packages/main/src/output.txt b/testrepo/packages/main/src/output.txt
index 054b666..999ee65 100644
--- a/testrepo/packages/main/src/output.txt
+++ b/testrepo/packages/main/src/output.txt
@@ -1,3 +1,4 @@
+Hello world
 01
 02
 a
diff --git a/testrepo/packages/new-namespace/bsconfig.json b/testrepo/packages/new-namespace/bsconfig.json
index 075d7fa..3b796b9 100644
--- a/testrepo/packages/new-namespace/bsconfig.json
+++ b/testrepo/packages/new-namespace/bsconfig.json
@@ -10,5 +10,6 @@
     "module": "es6",
     "in-source": true
   },
+  "bs-dependencies": ["@testrepo/dep01"],
   "suffix": ".bs.js"
 }
diff --git a/tests/compile.sh b/tests/compile.sh
index 955e1a4..b14d1a0 100755
--- a/tests/compile.sh
+++ b/tests/compile.sh
@@ -1,3 +1,4 @@
+#!/bin/bash
 cd $(dirname $0)
 source "./utils.sh"
 cd ../testrepo
@@ -52,6 +53,12 @@ replace "s/$(pwd | sed "s/\//\\\\\//g")//g" ../tests/snapshots/remove-file.txt
 git checkout -- packages/dep02/src/Dep02.res
 rewatch build &> /dev/null
 
+# it should show an error when we have a dependency cycle
+echo 'Dep01.log()' >> packages/new-namespace/src/NS_alias.res
+rewatch build --no-timing=true &> ../tests/snapshots/dependency-cycle.txt
+git checkout -- packages/new-namespace/src/NS_alias.res
+rewatch build &> /dev/null
+
 # make sure we don't have changes in the test repo
 if git diff --exit-code ./; 
 then
diff --git a/tests/snapshots/dependency-cycle.txt b/tests/snapshots/dependency-cycle.txt
new file mode 100644
index 0000000..651352b
--- /dev/null
+++ b/tests/snapshots/dependency-cycle.txt
@@ -0,0 +1,9 @@
+[1/7] 🌴  Building package tree...
[1/7] ️✅  Built package tree in 0.00s
+[2/7] 🔍  Finding source files...
[2/7] ️✅  Found source files in 0.00s
+[3/7] 🧹  Cleaning up previous build...
[3/7] ️✅  Cleaned 0/9 0.00s
+
[4/7] ️✅  Parsed 1 source files in 0.00s
+
[5/7] ️✅  Collected deps in 0.00s
+
[6/7] ️🛑  Compiled 0 modules in 0.00s
+
+Can't continue... Found a circular dependency in your code:
+Dep01 -> Dep02 -> NS -> NewNamespace.NS_alias -> Dep01