diff --git a/README.rst b/README.rst
index f33a16b2..7c866c21 100644
--- a/README.rst
+++ b/README.rst
@@ -389,7 +389,7 @@ Reference
 
 ``fill()`` -> int
    Adds zeros to the end of the bitarray, such that the length of the bitarray
-   is not a multiple of 8.  Returns the number of bits added (0..7).
+   will be a multiple of 8.  Returns the number of bits added (0..7).
 
 
 ``frombytes(bytes)``
diff --git a/bitarray/_bitarray.c b/bitarray/_bitarray.c
index d2c19cb9..1d3ab86d 100644
--- a/bitarray/_bitarray.c
+++ b/bitarray/_bitarray.c
@@ -1267,7 +1267,7 @@ PyDoc_STRVAR(fill_doc,
 "fill() -> int\n\
 \n\
 Adds zeros to the end of the bitarray, such that the length of the bitarray\n\
-is not a multiple of 8.  Returns the number of bits added (0..7).");
+will be a multiple of 8.  Returns the number of bits added (0..7).");
 
 
 static PyObject *