diff --git a/arraycontext/fake_numpy.py b/arraycontext/fake_numpy.py
index cf416fa1461ad8c476c99d3333f3db7bdb6983da..a73716a1bd0cfcfe4329851fbb2b682eefc1ba01 100644
--- a/arraycontext/fake_numpy.py
+++ b/arraycontext/fake_numpy.py
@@ -86,7 +86,7 @@ class BaseFakeNumpyNamespace:
 
         # Miscellaneous
         "convolve", "clip", "sqrt", "cbrt", "square", "absolute", "abs", "fabs",
-        "sign", "heaviside", "maximum", "fmax", "nan_to_num",
+        "sign", "heaviside", "maximum", "fmax", "nan_to_num", "isnan",
 
         # FIXME:
         # "interp",
diff --git a/test/test_arraycontext.py b/test/test_arraycontext.py
index ebc8dc49038c15c64fac8a939ba85808f01d386c..9c63e5e27854bdac19bac561fdc168d34d6c5bd1 100644
--- a/test/test_arraycontext.py
+++ b/test/test_arraycontext.py
@@ -367,6 +367,7 @@ def assert_close_to_numpy_in_containers(actx, op, args):
             ("abs", 1, np.complex128),
             ("sum", 1, np.float64),
             ("sum", 1, np.complex64),
+            ("isnan", 1, np.float64),
             ])
 def test_array_context_np_workalike(actx_factory, sym_name, n_args, dtype):
     actx = actx_factory()