diff --git a/Objects/stringlib/README.txt b/Objects/stringlib/README.txt
index c884ec3..ab506d6 100644
--- a/Objects/stringlib/README.txt
+++ b/Objects/stringlib/README.txt
@@ -13,7 +13,8 @@
 
 STRINGLIB_EMPTY
 
-    a PyObject representing the empty string
+    a PyObject representing the empty string, only to be used if
+    STRINGLIB_MUTABLE is 0
 
 Py_ssize_t STRINGLIB_LEN(PyObject*)
 
@@ -31,9 +32,9 @@
 
 int STRINGLIB_CHECK_EXACT(PyObject *)
 
-    returns true if the object is an instance of our type, not a subclass.
+    returns true if the object is an instance of our type, not a subclass
 
 STRINGLIB_MUTABLE
 
-    Must be 0 or 1 to tell the cpp macros in stringlib code if the object
-    being operated on is mutable or not.
+    must be 0 or 1 to tell the cpp macros in stringlib code if the object
+    being operated on is mutable or not