diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 26f492bcf10..23daee979f7 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -420,6 +420,10 @@ jobs:
         run: make test
         working-directory: ./test/running_modules
 
+      - name: test/multi_namespace
+        run: ./test.sh
+        working-directory: ./test/multi_namespace
+
       - name: Test FFI in subdirectories
         run: make
         working-directory: ./test/subdir_ffi
diff --git a/compiler-cli/src/publish.rs b/compiler-cli/src/publish.rs
index 299b1b82190..2965f4bcf64 100644
--- a/compiler-cli/src/publish.rs
+++ b/compiler-cli/src/publish.rs
@@ -5,7 +5,7 @@ use gleam_core::{
     build::{Codegen, Compile, Mode, Options, Package, Target},
     config::{PackageConfig, SpdxLicense},
     docs::DocContext,
-    error::SmallVersion,
+    error::{wrap, SmallVersion},
     hex,
     paths::{self, ProjectPaths},
     requirement::Requirement,
@@ -56,6 +56,7 @@ impl PublishCommand {
         } = do_build_hex_tarball(&paths, &mut config)?;
 
         check_for_name_squatting(&compile_result)?;
+        check_for_multiple_top_level_modules(&compile_result, i_am_sure)?;
 
         // Build HTML documentation
         let docs_tarball = fs::create_tar_archive(docs::build_documentation(
@@ -123,6 +124,50 @@ fn check_for_name_squatting(package: &Package) -> Result<(), Error> {
     Ok(())
 }
 
+fn check_for_multiple_top_level_modules(package: &Package, i_am_sure: bool) -> Result<(), Error> {
+    // Collect top-level module names
+    let mut top_level_module_names = package
+        .modules
+        .iter()
+        .filter_map(|module| module.name.split('/').next())
+        .collect::<Vec<_>>();
+
+    // Remove duplicates
+    top_level_module_names.sort_unstable();
+    top_level_module_names.dedup();
+
+    // If more than one top-level module name is found, prompt for confirmation
+    if top_level_module_names.len() > 1 {
+        let text = wrap(&format!(
+            "Your package defines multiple top-level modules: {}.
+
+Defining multiple top-level modules can lead to namespace pollution \
+and potential conflicts for consumers.
+
+To fix this, move all your modules under a single top-level module of your choice.
+
+For example:
+  src/{1}.gleam
+  src/{1}/module1.gleam
+  src/{1}/module2.gleam",
+            top_level_module_names.join(", "),
+            package.config.name
+        ));
+        println!("{text}\n");
+
+        let should_publish =
+            i_am_sure || cli::confirm("\nDo you wish to continue publishing this package?")?;
+        println!();
+
+        if !should_publish {
+            println!("Not publishing.");
+            std::process::exit(0);
+        }
+    }
+
+    Ok(())
+}
+
 fn check_repo_url(config: &PackageConfig, i_am_sure: bool) -> Result<bool, Error> {
     let Some(url) = config.repository.url() else {
         return Ok(true);
diff --git a/test/multi_namespace/.gitignore b/test/multi_namespace/.gitignore
new file mode 100644
index 00000000000..c1dc9b0dd00
--- /dev/null
+++ b/test/multi_namespace/.gitignore
@@ -0,0 +1,3 @@
+*.beam
+*.ez
+build
diff --git a/test/multi_namespace/gleam.toml b/test/multi_namespace/gleam.toml
new file mode 100644
index 00000000000..7e87bd8cedd
--- /dev/null
+++ b/test/multi_namespace/gleam.toml
@@ -0,0 +1,4 @@
+name = "multi_namespace"
+version = "1.0.0"
+description = "Test project for multi namespace"
+licences = ["Apache-2.0"]
diff --git a/test/multi_namespace/manifest.toml b/test/multi_namespace/manifest.toml
new file mode 100644
index 00000000000..c5d779a3f81
--- /dev/null
+++ b/test/multi_namespace/manifest.toml
@@ -0,0 +1,7 @@
+# This file was generated by Gleam
+# You typically do not need to edit this file
+
+packages = [
+]
+
+[requirements]
diff --git a/test/multi_namespace/src/multi_namespace.gleam b/test/multi_namespace/src/multi_namespace.gleam
new file mode 100644
index 00000000000..e68bfe18658
--- /dev/null
+++ b/test/multi_namespace/src/multi_namespace.gleam
@@ -0,0 +1,3 @@
+pub fn main() {
+  "Hello from multi_namespace!"
+}
diff --git a/test/multi_namespace/src/second.gleam b/test/multi_namespace/src/second.gleam
new file mode 100644
index 00000000000..d0737279e39
--- /dev/null
+++ b/test/multi_namespace/src/second.gleam
@@ -0,0 +1,3 @@
+pub fn main() {
+  "Hello from second!"
+}
diff --git a/test/multi_namespace/test.sh b/test/multi_namespace/test.sh
new file mode 100755
index 00000000000..91560f63ce6
--- /dev/null
+++ b/test/multi_namespace/test.sh
@@ -0,0 +1,26 @@
+#!/bin/sh
+
+set -eu
+
+GLEAM_COMMAND=${GLEAM_COMMAND:-"cargo run --quiet --"}
+
+g() {
+	echo "Running: $GLEAM_COMMAND $@"
+	$GLEAM_COMMAND "$@"
+}
+
+echo Resetting the build directory to get to a known state
+rm -fr build
+
+echo Running publish should not publish anything
+output=$(yes "n" | g publish)
+if echo "$output" | grep -q "Your package defines multiple top-level modules"; then
+    echo "Publish was correctly prevented with warning"
+else
+    echo "Expected publish to be aborted"
+    exit 1
+fi
+
+echo
+echo Success! 💖
+echo