diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 949205a..7871043 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -11701,7 +11701,11 @@
 PyDoc_STRVAR(index__doc__,
              "S.index(sub[, start[, end]]) -> int\n\
 \n\
-Like S.find() but raise ValueError when the substring is not found.");
+Return the lowest index in S where substring sub is found, \n\
+such that sub is contained within S[start:end].  Optional\n\
+arguments start and end are interpreted as in slice notation.\n\
+\n\
+Raises ValueError when the substring is not found.");
 
 static PyObject *
 unicode_index(PyObject *self, PyObject *args)
@@ -12758,7 +12762,11 @@
 PyDoc_STRVAR(rindex__doc__,
              "S.rindex(sub[, start[, end]]) -> int\n\
 \n\
-Like S.rfind() but raise ValueError when the substring is not found.");
+Return the highest index in S where substring sub is found,\n\
+such that sub is contained within S[start:end].  Optional\n\
+arguments start and end are interpreted as in slice notation.\n\
+\n\
+Raises ValueError when the substring is not found.");
 
 static PyObject *
 unicode_rindex(PyObject *self, PyObject *args)