diff --git a/numpy/f2py/__init__.py b/numpy/f2py/__init__.py
index e34dd99aec1c..1367d01881c1 100644
--- a/numpy/f2py/__init__.py
+++ b/numpy/f2py/__init__.py
@@ -16,7 +16,7 @@
 
 from numpy.exceptions import VisibleDeprecationWarning
 
-from . import diagnose, f2py2e
+from . import f2py2e
 
 run_main = f2py2e.run_main
 main = f2py2e.main
diff --git a/numpy/f2py/diagnose.py b/numpy/f2py/diagnose.py
index 7eb1697cc787..62013fccdd69 100644
--- a/numpy/f2py/diagnose.py
+++ b/numpy/f2py/diagnose.py
@@ -2,6 +2,18 @@
 import os
 import sys
 import tempfile
+import warnings
+
+# NumPy 2.3.0, 2025-05-01
+warnings.warn('The module numpy.f2py.diagnose is deprecated since NumPy 2.3.0.',
+              DeprecationWarning,
+              stacklevel=2)
+
+
+def run_command(cmd):
+    print(f'Running {cmd!r}:')
+    os.system(cmd)
+    print('------')
 
 
 def run():