diff --git a/compiler/GHC/Driver/Make.hs b/compiler/GHC/Driver/Make.hs
index 7c0c1216878bd13fb16c2718320501fc8b1cf7ed..067b0609faac285fa220eff8129e93618b245a08 100644
--- a/compiler/GHC/Driver/Make.hs
+++ b/compiler/GHC/Driver/Make.hs
@@ -340,10 +340,12 @@ warnMissingHomeModules dflags targets mod_graph =
     -- Note also that we can't always infer the associated module name
     -- directly from the filename argument.  See #13727.
     is_known_module mod =
-      (Map.lookup (moduleName (ms_mod mod)) mod_targets == Just (ms_unitid mod))
+      is_module_target mod
       ||
       maybe False is_file_target (ml_hs_file (ms_location mod))
 
+    is_module_target mod = (moduleName (ms_mod mod), ms_unitid mod) `Set.member` mod_targets
+
     is_file_target file = Set.member (withoutExt file) file_targets
 
     file_targets = Set.fromList (mapMaybe file_target targets)
@@ -354,7 +356,7 @@ warnMissingHomeModules dflags targets mod_graph =
         TargetFile file _ ->
           Just (withoutExt (augmentByWorkingDirectory dflags file))
 
-    mod_targets = Map.fromList (mod_target <$> targets)
+    mod_targets = Set.fromList (mod_target <$> targets)
 
     mod_target Target {targetUnitId, targetId} =
       case targetId of
diff --git a/testsuite/tests/driver/multipleHomeUnits/T25122/T25122.hs b/testsuite/tests/driver/multipleHomeUnits/T25122/T25122.hs
new file mode 100644
index 0000000000000000000000000000000000000000..62145c3eee0f1db38ab4578e869f83f28e03a192
--- /dev/null
+++ b/testsuite/tests/driver/multipleHomeUnits/T25122/T25122.hs
@@ -0,0 +1 @@
+module T25122 where
diff --git a/testsuite/tests/driver/multipleHomeUnits/all.T b/testsuite/tests/driver/multipleHomeUnits/all.T
index f748b6013dfaafb275613700142e3080c20a9c3e..6bfd151a1af875de5d878e4e165455ebf8b26561 100644
--- a/testsuite/tests/driver/multipleHomeUnits/all.T
+++ b/testsuite/tests/driver/multipleHomeUnits/all.T
@@ -71,6 +71,11 @@ test('multipleHomeUnits_shared', [extra_files([ 'A.hs', 'unitShared1', 'unitShar
 
 test('multipleHomeUnits_shared_ghci', [extra_files([ 'shared.script', 'A.hs', 'unitShared1', 'unitShared2']), extra_run_opts('-unit @unitShared1 -unit @unitShared2')], ghci_script, ['shared.script'])
 
+test('T25122',
+    [ extra_files(
+        [ 'T25122', 'unitSame1', 'unitSame2'])
+    ], multiunit_compile, [['unitSame1', 'unitSame2'], '-v0 -fhide-source-paths -Werror -Wmissing-home-modules'])
+
 
 
 
diff --git a/testsuite/tests/driver/multipleHomeUnits/unitSame1 b/testsuite/tests/driver/multipleHomeUnits/unitSame1
new file mode 100644
index 0000000000000000000000000000000000000000..96d32a2efab48211aebf0c680d3b3f2d738e019d
--- /dev/null
+++ b/testsuite/tests/driver/multipleHomeUnits/unitSame1
@@ -0,0 +1,3 @@
+T25122
+-iT25122
+-this-unit-id=s1
diff --git a/testsuite/tests/driver/multipleHomeUnits/unitSame2 b/testsuite/tests/driver/multipleHomeUnits/unitSame2
new file mode 100644
index 0000000000000000000000000000000000000000..e951afe57552a650936626e9b7319ee4be41f008
--- /dev/null
+++ b/testsuite/tests/driver/multipleHomeUnits/unitSame2
@@ -0,0 +1,3 @@
+T25122
+-iT25122
+-this-unit-id=u2