diff --git a/control/tests/xferfcn_test.py b/control/tests/xferfcn_test.py
index a9be040ab..89ceb9490 100644
--- a/control/tests/xferfcn_test.py
+++ b/control/tests/xferfcn_test.py
@@ -28,6 +28,21 @@ class TestXferFcn:
 
     # Tests for raising exceptions.
 
+    def test_zpk_complex_dtypes(self):
+        """Test zpk with complex64 and complex128 zeros/poles (Issue #1188)."""
+        P = ct.rss(5)
+        q1 = ct.zpk(zeros=P.zeros().astype(np.complex64),
+                    poles=P.poles().astype(np.complex64),
+                    gain=1, dt=0)
+        assert isinstance(q1, ct.TransferFunction)
+        assert "s^5" in str(q1)
+
+        q2 = ct.zpk(zeros=P.zeros().astype(np.complex128),
+                    poles=P.poles().astype(np.complex128),
+                    gain=1, dt=0)
+        assert isinstance(q2, ct.TransferFunction)
+        assert "s^5" in str(q2)
+
     def test_constructor_bad_input_type(self):
         """Give the constructor invalid input types."""
         # Single argument of the wrong type
diff --git a/control/xferfcn.py b/control/xferfcn.py
index ad9ea0554..fa792643b 100644
--- a/control/xferfcn.py
+++ b/control/xferfcn.py
@@ -1379,6 +1379,7 @@ def _tf_polynomial_to_string(coeffs, var='s'):
     thestr = "0"
 
     # Apply NumPy formatting
+    coeffs = np.asarray(coeffs, dtype=float)
     with np.printoptions(threshold=sys.maxsize):
         coeffs = eval(repr(coeffs))
 
@@ -2015,6 +2016,12 @@ def _clean_part(data, name="<unknown>"):
     # Check for coefficients that are ints and convert to floats
     for i in range(out.shape[0]):
         for j in range(out.shape[1]):
+            if np.iscomplexobj(out[i, j]):
+                if np.allclose(np.imag(out[i, j]), 0.0, atol=1e-10):
+                    out[i, j] = np.real(out[i, j]).astype(float)
+                else:
+                    raise TypeError(
+                        f"unsupported data type: {type(out[i, j][0])}")
             for k in range(len(out[i, j])):
                 if isinstance(out[i, j][k], (int, np.integer)):
                     out[i, j][k] = float(out[i, j][k])