diff --git a/mesonbuild/interpreter.py b/mesonbuild/interpreter.py
index 268a8eff9..adf79664a 100644
--- a/mesonbuild/interpreter.py
+++ b/mesonbuild/interpreter.py
@@ -1883,8 +1883,8 @@ to directly access options of other subprojects.''')
             raise InvalidCode('Second call to project().')
         if not self.is_subproject() and 'subproject_dir' in kwargs:
             spdirname = kwargs['subproject_dir']
-            if '/' in spdirname or '\\' in spdirname:
-                raise InterpreterException('Subproject_dir must not contain a path segment.')
+            if os.path.isabs(spdirname):
+                raise InterpreterException('Subproject_dir must not be an absolute path.')
             if spdirname.startswith('.'):
                 raise InterpreterException('Subproject_dir must not begin with a period.')
             self.subproject_dir = spdirname