diff --git a/sumpy/expansion/__init__.py b/sumpy/expansion/__init__.py
index 6407e3303e9b65280089a097577c79f9f59ed38b..6803e8a75b7b9d4e83974a044af878629561ff44 100644
--- a/sumpy/expansion/__init__.py
+++ b/sumpy/expansion/__init__.py
@@ -239,7 +239,7 @@ class CSEMatVecOperator(object):
     .. attribute:: from_input_coeffs_by_row
 
         An object of type ``List[List[Tuple[int, Any]]]``. Each element
-        in the list represents a row of the Matrix using a linear combination
+        in the list represents a row of the matrix using a linear combination
         of values from the input vector. Each element has the form
         ``(index of input vector, coeff)``.