diff --git a/data/test.schema.json b/data/test.schema.json
index 98ae44eeb..b5f6aba62 100644
--- a/data/test.schema.json
+++ b/data/test.schema.json
@@ -27,6 +27,7 @@
               "shared_lib",
               "python_lib",
               "python_limited_lib",
+              "python_bytecode",
               "pdb",
               "implib",
               "py_implib",
diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index 6c739ed0a..491f2a63d 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -1694,8 +1694,6 @@ class NinjaBackend(backends.Backend):
             # Without this, it will write it inside c_out_dir
             args += ['--vapi', os.path.join('..', target.vala_vapi)]
             valac_outputs.append(vapiname)
-            target.outputs += [target.vala_header, target.vala_vapi]
-            target.install_tag += ['devel', 'devel']
             # Install header and vapi to default locations if user requests this
             if len(target.install_dir) > 1 and target.install_dir[1] is True:
                 target.install_dir[1] = self.environment.get_includedir()
@@ -1706,8 +1704,6 @@ class NinjaBackend(backends.Backend):
                 girname = os.path.join(self.get_target_dir(target), target.vala_gir)
                 args += ['--gir', os.path.join('..', target.vala_gir)]
                 valac_outputs.append(girname)
-                target.outputs.append(target.vala_gir)
-                target.install_tag.append('devel')
                 # Install GIR to default location if requested by user
                 if len(target.install_dir) > 3 and target.install_dir[3] is True:
                     target.install_dir[3] = os.path.join(self.environment.get_datadir(), 'gir-1.0')
diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index edec75d90..09437037a 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -789,6 +789,12 @@ class BuildTarget(Target):
             # relocation-model=pic is rustc's default and Meson does not
             # currently have a way to disable PIC.
             self.pic = True
+        if 'vala' in self.compilers and self.is_linkable_target():
+            self.outputs += [self.vala_header, self.vala_vapi]
+            self.install_tag += ['devel', 'devel']
+            if self.vala_gir:
+                self.outputs.append(self.vala_gir)
+                self.install_tag.append('devel')
 
     def __repr__(self):
         repr_str = "<{0} {1}: {2}>"
@@ -1945,7 +1951,7 @@ class Executable(BuildTarget):
         self.filename = self.name
         if self.suffix:
             self.filename += '.' + self.suffix
-        self.outputs = [self.filename]
+        self.outputs[0] = self.filename
 
         # The import library this target will generate
         self.import_filename = None
@@ -2086,7 +2092,7 @@ class StaticLibrary(BuildTarget):
             else:
                 self.suffix = 'a'
         self.filename = self.prefix + self.name + '.' + self.suffix
-        self.outputs = [self.filename]
+        self.outputs[0] = self.filename
 
     def get_link_deps_mapping(self, prefix: str) -> T.Mapping[str, str]:
         return {}
diff --git a/run_project_tests.py b/run_project_tests.py
index 446dc12b8..8e0af2659 100755
--- a/run_project_tests.py
+++ b/run_project_tests.py
@@ -40,6 +40,7 @@ import time
 import typing as T
 import xml.etree.ElementTree as ET
 import collections
+import importlib.util
 
 from mesonbuild import build
 from mesonbuild import environment
@@ -169,7 +170,7 @@ class InstalledFile:
             return None
 
         # Handle the different types
-        if self.typ in {'py_implib', 'py_limited_implib', 'python_lib', 'python_limited_lib', 'python_file'}:
+        if self.typ in {'py_implib', 'py_limited_implib', 'python_lib', 'python_limited_lib', 'python_file', 'python_bytecode'}:
             val = p.as_posix()
             val = val.replace('@PYTHON_PLATLIB@', python.platlib)
             val = val.replace('@PYTHON_PURELIB@', python.purelib)
@@ -196,6 +197,8 @@ class InstalledFile:
                     return p.with_suffix('.dll.a')
                 else:
                     return None
+            if self.typ == 'python_bytecode':
+                return p.parent / importlib.util.cache_from_source(p.name)
         elif self.typ in {'file', 'dir'}:
             return p
         elif self.typ == 'shared_lib':
diff --git a/test cases/vala/7 shared library/lib/meson.build b/test cases/vala/7 shared library/lib/meson.build
index edeeb96d1..bbd3862f1 100644
--- a/test cases/vala/7 shared library/lib/meson.build	
+++ b/test cases/vala/7 shared library/lib/meson.build	
@@ -33,3 +33,8 @@ shared_library('installed_vala_onlyvapi', 'mylib.vala',
   dependencies : valadeps,
   install : true,
   install_dir : [false, false, join_paths(get_option('datadir'), 'vala', 'vapi')])
+
+# Regression test: Vala libraries were broken when also installing python modules.
+# https://gitlab.gnome.org/GNOME/gitg/-/issues/412
+python = import('python').find_installation()
+python.install_sources('source.py')
diff --git a/test cases/vala/7 shared library/lib/source.py b/test cases/vala/7 shared library/lib/source.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/test cases/vala/7 shared library/test.json b/test cases/vala/7 shared library/test.json
index eee3c3dca..08bd70734 100644
--- a/test cases/vala/7 shared library/test.json	
+++ b/test cases/vala/7 shared library/test.json	
@@ -9,6 +9,8 @@
     {"type": "file", "file": "usr/include/installed_vala_onlyh.h"},
     {"type": "file", "file": "usr/share/vala/vapi/installed_vala_all.vapi"},
     {"type": "file", "file": "usr/share/vala-1.0/vapi/installed_vala_all_nolib.vapi"},
-    {"type": "file", "file": "usr/share/vala/vapi/installed_vala_onlyvapi.vapi"}
+    {"type": "file", "file": "usr/share/vala/vapi/installed_vala_onlyvapi.vapi"},
+    {"type": "python_file", "file": "usr/@PYTHON_PURELIB@/source.py"},
+    {"type": "python_bytecode", "file": "usr/@PYTHON_PURELIB@/source.py"}
   ]
 }