diff --git a/control/statefbk.py b/control/statefbk.py
index b6e9c9655..6625c56af 100644
--- a/control/statefbk.py
+++ b/control/statefbk.py
@@ -252,7 +252,7 @@ def place_acker(A, B, poles):
     K = np.linalg.solve(ct, pmat)
 
     K = K[-1, :]                # Extract the last row
-    return K
+    return _ssmatrix(K)
 
 
 def lqr(*args, **kwargs):