diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 8d7147b..73b0220 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -539,7 +539,7 @@
 Evaluate the source in the context of globals and locals.\n\
 The source may be a string representing a Python expression\n\
 or a code object as returned by compile().\n\
-The globals must be a dictionary and locals can be any mappping,\n\
+The globals must be a dictionary and locals can be any mapping,\n\
 defaulting to the current globals and locals.\n\
 If only globals is given, locals defaults to it.\n");
 
@@ -1972,10 +1972,11 @@
 }
 
 PyDoc_STRVAR(sum_doc,
-"sum(sequence, start=0) -> value\n\
+"sum(sequence[, start]) -> value\n\
 \n\
 Returns the sum of a sequence of numbers (NOT strings) plus the value\n\
-of parameter 'start'.  When the sequence is empty, returns start.");
+of parameter 'start' (which defaults to 0).  When the sequence is\n\
+empty, returns start.");
 
 
 static PyObject *