diff --git a/neurodsp/sim/periodic.py b/neurodsp/sim/periodic.py
index 92e7d2d5..c94a51ed 100644
--- a/neurodsp/sim/periodic.py
+++ b/neurodsp/sim/periodic.py
@@ -38,6 +38,13 @@ def sim_oscillation(n_seconds, fs, freq, cycle='sine', phase=0, **cycle_params):
     sig : 1d array
         Simulated oscillation.
 
+    Notes
+    -----
+	Depending on the requested frequency (`freq`), sampling rate (`fs`), and signal
+	length (`n_seconds`), the simulated signal may have a non-integer number of cycles.
+	If so, the frequency-domain representation of the signal will have some power in non-simulated
+	frequencies. To avoid this, choose `n_seconds` and `fs` to create an integer number of cycles.
+
     Examples
     --------
     Simulate a continuous sinusoidal oscillation at 5 Hz:
diff --git a/neurodsp/sim/utils.py b/neurodsp/sim/utils.py
new file mode 100644
index 00000000..c422bae7
--- /dev/null
+++ b/neurodsp/sim/utils.py
@@ -0,0 +1,30 @@
+"""Utility functions for simulations."""
+
+###################################################################################################
+###################################################################################################
+
+def check_osc_def(n_seconds, fs, freq):
+    """Check whether a requested oscillation definition will have an integer number of cycles.
+
+    Parameters
+    ----------
+    n_seconds : float
+        Simulation time, in seconds.
+    fs : float
+        Signal sampling rate, in Hz.
+    freq : float
+        Oscillation frequency.
+
+    Returns
+    -------
+    bool
+        Whether the definition will have an integer number of cycles.
+    """
+
+    # Sampling rate check: check if the number of samples per cycle is an integer
+    srate_check = (fs/freq).is_integer()
+
+    # Time check: check if signal length matches an integer number of cycles
+    time_check = (n_seconds * freq).is_integer()
+
+    return srate_check and time_check
diff --git a/neurodsp/tests/sim/test_utils.py b/neurodsp/tests/sim/test_utils.py
new file mode 100644
index 00000000..bf04871b
--- /dev/null
+++ b/neurodsp/tests/sim/test_utils.py
@@ -0,0 +1,24 @@
+"""Tests for neurodsp.sim.utils."""
+
+from neurodsp.sim.utils import *
+
+###################################################################################################
+###################################################################################################
+
+def test_check_osc_def():
+
+	n_seconds = 1.0
+	fs = 100
+	freq = 10
+
+	# Check definition that should pass
+	assert check_osc_def(n_seconds, fs, freq)
+
+	# Check a definition that should fail the sampling rate check
+	assert not check_osc_def(1.05, fs, freq)
+
+	# Check a definition that should fail the time check
+	assert not check_osc_def(n_seconds, 1111, freq)
+
+	# Check a definition that should fail both checks
+	assert not check_osc_def(1.05, 1111, freq)