diff --git a/CHANGELOG.md b/CHANGELOG.md
index fff97c43a..cc7ca4dbf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,7 @@ New features:
 - Add `--open` flag to `spago docs` which opens generated docs in browser (#379)
 - Support building for alternate backends (#355). E.g: Use `backend = "psgo"` entry in `spago.dhall` to compile with `psgo`
 - Add `--no-comments` flag to `spago init` which strips comments from the generated `spago.dhall` and `packages.dhall` configs (#417)
+- Make `spago verify-set` compile everything, to detect duplicate module names (#438)
 - Add shared output folder to reduce build duplication. Pass `--no-share-output` flag to `spago build` to disable (#377)
 - Fix confusing warning when trying to `spago install` a package already present in project dependencies list (#436)
 
diff --git a/app/Spago.hs b/app/Spago.hs
index fdb5ab575..df1a9168e 100644
--- a/app/Spago.hs
+++ b/app/Spago.hs
@@ -21,7 +21,7 @@ import           Spago.DryRun        (DryRun (..))
 import qualified Spago.GitHub
 import           Spago.GlobalCache   (CacheFlag (..))
 import           Spago.Messages      as Messages
-import           Spago.Packages      (JsonFlag (..), PackagesFilter (..))
+import           Spago.Packages      (CheckModulesUnique (..), JsonFlag (..), PackagesFilter (..))
 import qualified Spago.Packages
 import qualified Spago.Purs          as Purs
 import           Spago.Types
@@ -60,7 +60,7 @@ data Command
   | Verify (Maybe CacheFlag) PackageName
 
   -- | Verify that the Package Set is correct
-  | VerifySet (Maybe CacheFlag)
+  | VerifySet (Maybe CacheFlag) CheckModulesUnique
 
   -- | Test the project with some module, default Test.Main
   | Test (Maybe ModuleName) BuildOptions [ExtraArg]
@@ -143,6 +143,7 @@ parser = do
     openDocs    = bool NoOpenDocs DoOpenDocs <$> CLI.switch "open" 'o' "Open generated documentation in browser (for HTML format only)"
     noComments  = bool WithComments NoComments <$> CLI.switch "no-comments" 'C' "Generate package.dhall and spago.dhall files without tutorial comments"
     configPath  = CLI.optional $ CLI.optText "config" 'x' "Optional config path to be used instead of the default spago.dhall"
+    chkModsUniq = bool DoCheckModulesUnique NoCheckModulesUnique <$> CLI.switch "no-check-modules-unique" 'M' "Skip checking whether modules names are unique across all packages."
 
     mainModule  = CLI.optional $ CLI.opt (Just . ModuleName) "main" 'm' "Module to be used as the application's entry point"
     toTarget    = CLI.optional $ CLI.opt (Just . TargetPath) "to" 't' "The target file path"
@@ -264,7 +265,7 @@ parser = do
     verifySet =
       ( "verify-set"
       , "Verify that the whole Package Set builds correctly"
-      , VerifySet <$> cacheFlag
+      , VerifySet <$> cacheFlag <*> chkModsUniq
       )
 
     upgradeSet =
@@ -338,8 +339,8 @@ main = do
       Install cacheConfig packageNames      -> Spago.Packages.install cacheConfig packageNames
       ListPackages packagesFilter jsonFlag  -> Spago.Packages.listPackages packagesFilter jsonFlag
       Sources                               -> Spago.Packages.sources
-      Verify cacheConfig package            -> Spago.Packages.verify cacheConfig (Just package)
-      VerifySet cacheConfig                 -> Spago.Packages.verify cacheConfig Nothing
+      Verify cacheConfig package            -> Spago.Packages.verify cacheConfig NoCheckModulesUnique (Just package)
+      VerifySet cacheConfig chkModsUniq     -> Spago.Packages.verify cacheConfig chkModsUniq Nothing
       PackageSetUpgrade                     -> Spago.Packages.upgradePackageSet
       Freeze                                -> Spago.Packages.freeze Spago.Packages.packagesPath
       Build buildOptions                    -> Spago.Build.build buildOptions Nothing
diff --git a/src/Spago/Packages.hs b/src/Spago/Packages.hs
index cf46df904..0cd6db31f 100644
--- a/src/Spago/Packages.hs
+++ b/src/Spago/Packages.hs
@@ -12,6 +12,7 @@ module Spago.Packages
   , PackageSet.freeze
   , PackageSet.packagesPath
   , PackagesFilter(..)
+  , CheckModulesUnique(..)
   , JsonFlag(..)
   , DepsOnly(..)
   ) where
@@ -306,13 +307,16 @@ sources = do
   pure ()
 
 
-verify :: Spago m => Maybe CacheFlag -> Maybe PackageName -> m ()
-verify cacheFlag maybePackage = do
+data CheckModulesUnique = DoCheckModulesUnique | NoCheckModulesUnique
+
+verify :: Spago m => Maybe CacheFlag -> CheckModulesUnique -> Maybe PackageName -> m ()
+verify cacheFlag chkModsUniq maybePackage = do
   echoDebug "Running `spago verify`"
   Config{ packageSet = packageSet@PackageSet{..}, ..} <- Config.ensureConfig
   case maybePackage of
     -- If no package is specified, verify all of them
-    Nothing -> verifyPackages packageSet (Map.toList packagesDB)
+    Nothing -> do
+      verifyPackages packageSet (Map.toList packagesDB)
     -- In case we have a package, search in the package set for it
     Just packageName -> do
       case Map.lookup packageName packagesDB of
@@ -325,6 +329,9 @@ verify cacheFlag maybePackage = do
           reverseDeps <- liftIO $ getReverseDeps packageSet packageName
           let toVerify = [(packageName, package)] <> reverseDeps
           verifyPackages packageSet toVerify
+  case chkModsUniq of
+    DoCheckModulesUnique -> compileEverything packageSet
+    NoCheckModulesUnique -> pure ()
   where
     verifyPackages :: Spago m => PackageSet -> [(PackageName, Package)] -> m ()
     verifyPackages packageSet packages = do
@@ -340,3 +347,12 @@ verify cacheFlag maybePackage = do
       echo $ "Verifying package " <> quotedName
       Purs.compile globs []
       echo $ "Successfully verified " <> quotedName
+
+    compileEverything :: Spago m => PackageSet -> m ()
+    compileEverything PackageSet{..} = do
+      let deps = Map.toList packagesDB
+          globs = getGlobs deps DepsOnly []
+      Fetch.fetchPackages cacheFlag deps packagesMinPursVersion
+      echo "Compiling everything (will fail if module names conflict)"
+      Purs.compile globs []
+      echo "Successfully compiled everything"