diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index 353984b14..3a1ab3f07 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -1614,7 +1614,9 @@ class NinjaBackend(backends.Backend):
             rel_src = src.rel_to_builddir(self.build_to_src)
             rel_srcs.append(rel_src)
 
-            plain_class_path = src.fname[:-4] + 'class'
+            # Preserve any additional path components on top of the target's subdir
+            plain_class_path = os.path.relpath(src.relative_name(), target.get_subdir())
+            plain_class_path = plain_class_path[:-4] + 'class'
             plain_class_paths.append(plain_class_path)
             rel_obj = os.path.join(self.get_target_private_dir(target), plain_class_path)
             rel_objs.append(rel_obj)
diff --git a/test cases/java/11 build subdir/com-mesonbuild-HelloWorldMainLauncherClass.java b/test cases/java/11 build subdir/com-mesonbuild-HelloWorldMainLauncherClass.java
new file mode 100644
index 000000000..0e81bb7d5
--- /dev/null
+++ b/test cases/java/11 build subdir/com-mesonbuild-HelloWorldMainLauncherClass.java	
@@ -0,0 +1,7 @@
+package com.mesonbuild;
+
+public class HelloWorldMainLauncherClass {
+    public static void main(String [] args) {
+        System.out.println("hello nanowar of steel");
+    }
+}
diff --git a/test cases/java/11 build subdir/copyfile.py b/test cases/java/11 build subdir/copyfile.py
new file mode 100644
index 000000000..ff42ac359
--- /dev/null
+++ b/test cases/java/11 build subdir/copyfile.py	
@@ -0,0 +1,6 @@
+#!/usr/bin/env python3
+
+import sys
+import shutil
+
+shutil.copyfile(sys.argv[1], sys.argv[2])
diff --git a/test cases/java/11 build subdir/meson.build b/test cases/java/11 build subdir/meson.build
new file mode 100644
index 000000000..762d037f6
--- /dev/null
+++ b/test cases/java/11 build subdir/meson.build	
@@ -0,0 +1,13 @@
+project('build subdir java', 'java')
+
+copyfile = find_program('copyfile.py')
+
+generated = custom_target(
+  command: [copyfile, '@INPUT@', '@OUTPUT@'],
+  input: 'com-mesonbuild-HelloWorldMainLauncherClass.java',
+  output: 'HelloWorldMainLauncherClass.java',
+  build_subdir: 'com/mesonbuild',
+)
+
+jar('hello', generated,
+  main_class: 'com.mesonbuild.HelloWorldMainLauncherClass')
diff --git a/unittests/platformagnostictests.py b/unittests/platformagnostictests.py
index f6cd77952..c825907c2 100644
--- a/unittests/platformagnostictests.py
+++ b/unittests/platformagnostictests.py
@@ -15,7 +15,7 @@ from unittest import skipIf, SkipTest
 from pathlib import Path
 
 from .baseplatformtests import BasePlatformTests
-from .helpers import IS_CI
+from .helpers import *
 from mesonbuild.mesonlib import EnvironmentVariables, ExecutableSerialisation, MesonException, is_linux, python_command, windows_proof_rmtree
 from mesonbuild.mformat import Formatter, match_path
 from mesonbuild.optinterpreter import OptionInterpreter, OptionException
@@ -626,3 +626,11 @@ class PlatformAgnosticTests(BasePlatformTests):
 
         self.init(testdir)
         self.build()
+
+    @skip_if_not_language('java')
+    def test_java_build_subdir_correct_deps(self):
+        """Test that jar() with build_subdir sources does not rebuild unnecessarily."""
+        testdir = os.path.join(self.src_root, 'test cases', 'java', '11 build subdir')
+        self.init(testdir)
+        self.build()
+        self.assertBuildIsNoop()