diff --git a/src/sage/matrix/matrix_complex_ball_dense.pyx b/src/sage/matrix/matrix_complex_ball_dense.pyx
index d9c0dc2db3c..cc10daab8c7 100644
--- a/src/sage/matrix/matrix_complex_ball_dense.pyx
+++ b/src/sage/matrix/matrix_complex_ball_dense.pyx
@@ -105,6 +105,10 @@ cdef class Matrix_complex_ball_dense(matrix_dense.Matrix_dense):
 
         sage: from sage.rings.complex_ball_acb import ComplexBallField # optional - arb
         sage: CBF = ComplexBallField() # optional - arb
+        doctest:...: FutureWarning: This class/method/function is marked as
+        experimental. It, its functionality or its interface might change
+        without a formal deprecation.
+        See http://trac.sagemath.org/17218 for details.
         sage: MatrixSpace(CBF, 3)(2) # optional - arb
         [2.000000000000000                 0                 0]
         [                0 2.000000000000000                 0]