diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index 6200235fefbc..0d606e60a45a 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -2457,7 +2457,7 @@ def process_kwargs(self, kwargs, backend):
             if not isinstance(self.install, bool):
                 raise InvalidArguments('"install" must be boolean.')
             if self.install:
-                if 'install_dir' not in kwargs:
+                if not kwargs.get('install_dir', False):
                     raise InvalidArguments('"install_dir" must be specified '
                                            'when installing a target')