diff --git a/docs/changes/837.bugfix.rst b/docs/changes/837.bugfix.rst
new file mode 100644
index 000000000..bdebe104b
--- /dev/null
+++ b/docs/changes/837.bugfix.rst
@@ -0,0 +1,3 @@
+The ``fold_events`` function now checks if the keyword arguments (`kwargs`) are in the list of optional parameters.
+If any unidentified keys are present, it raises a `ValueError`. 
+This fix ensures that the function only accepts valid optional parameters and provides a clear error message for unsupported keys.
diff --git a/stingray/pulse/pulsar.py b/stingray/pulse/pulsar.py
index 4e84ab8bd..fce5abc41 100644
--- a/stingray/pulse/pulsar.py
+++ b/stingray/pulse/pulsar.py
@@ -113,8 +113,8 @@ def pulse_phase(times, *frequency_derivatives, **opts):
 
     """
 
-    ph0 = _default_value_if_no_key(opts, "ph0", 0)
-    to_1 = _default_value_if_no_key(opts, "to_1", True)
+    ph0 = opts.pop("ph0", 0)
+    to_1 = opts.pop("to_1", True)
     ph = ph0
 
     for i_f, f in enumerate(frequency_derivatives):
@@ -263,18 +263,24 @@ def fold_events(times, *frequency_derivatives, **opts):
     profile_err : array of floats
         The uncertainties on the pulse profile
     """
-    mode = _default_value_if_no_key(opts, "mode", "ef")
-    nbin = _default_value_if_no_key(opts, "nbin", 16)
-    weights = _default_value_if_no_key(opts, "weights", 1)
+
+    mode = opts.pop("mode", "ef")
+    nbin = opts.pop("nbin", 16)
+    weights = opts.pop("weights", 1)
     # If no key is passed, *or gti is None*, defaults to the
     # initial and final event
-    gti = _default_value_if_no_key(opts, "gti", None)
+    gti = opts.pop("gti", None)
     if gti is None:
         gti = [[times[0], times[-1]]]
     # Be safe if gtis are a list
     gti = np.asanyarray(gti)
-    ref_time = _default_value_if_no_key(opts, "ref_time", 0)
-    expocorr = _default_value_if_no_key(opts, "expocorr", False)
+    ref_time = opts.pop("ref_time", 0)
+    expocorr = opts.pop("expocorr", False)
+
+    if opts:
+        raise ValueError(
+            f"Unidentified keyword(s) to fold_events: {', '.join([k for k in opts.keys()])} \n Please refer to the description of the function for optional parameters."
+        )
 
     if not isinstance(weights, Iterable):
         weights *= np.ones(len(times))
diff --git a/stingray/pulse/tests/test_search.py b/stingray/pulse/tests/test_search.py
index 749cd1934..1e35071e5 100644
--- a/stingray/pulse/tests/test_search.py
+++ b/stingray/pulse/tests/test_search.py
@@ -111,6 +111,12 @@ def test_plot_phaseogram_direct(self):
         plt.savefig("phaseogram_direct.png")
         plt.close(plt.gcf())
 
+    def test_search_wrong_key_fails(self):
+        with pytest.raises(
+            ValueError, match=r"Unidentified keyword\(s\) to fold_events: fdot, fddot"
+        ):
+            phase, prof, _ = fold_events(self.event_times, self.pulse_frequency, fdot=12, fddot=34)
+
     def test_plot_profile(self):
         phase, prof, _ = fold_events(self.event_times, self.pulse_frequency)
         ax = plot_profile(phase, prof)
@@ -120,7 +126,7 @@ def test_plot_profile(self):
     def test_plot_profile_existing_ax(self):
         fig = plt.figure("Pulse profile")
         ax = plt.subplot()
-        phase, prof, _ = fold_events(self.event_times, self.pulse_frequency, ax=ax)
+        phase, prof, _ = fold_events(self.event_times, self.pulse_frequency)
         ax = plot_profile(phase, prof, ax=ax)
         plt.savefig("profile_existing_ax.png")
         plt.close(fig)
@@ -128,7 +134,7 @@ def test_plot_profile_existing_ax(self):
     def test_plot_profile_errorbars(self):
         fig = plt.figure("Pulse profile")
         ax = plt.subplot()
-        phase, prof, err = fold_events(self.event_times, self.pulse_frequency, ax=ax)
+        phase, prof, err = fold_events(self.event_times, self.pulse_frequency)
 
         ax = plot_profile(phase, prof, err=err, ax=ax)
         plt.savefig("profile_errorbars.png")