diff --git a/README.rst b/README.rst
index 7e95101..e0925d4 100644
--- a/README.rst
+++ b/README.rst
@@ -127,15 +127,22 @@ max_concurrent
 
 Global Options
 --------------
-The following options applies to all checkers.
+The following options apply to all checkers.
 
 prefix
-  Strip the prefix string if the version string starts with it.
+  Strip the prefix string if the version string starts with it. Otherwise the
+  version string is returned as-is.
 
 from_pattern, to_pattern
   Both are Python-compatible regular expressions. If ``from_pattern`` is found
   in the version string, it will be replaced with ``to_pattern``.
 
+If both ``prefix`` and ``from_pattern``/``to_pattern`` are used,
+``from_pattern``/``to_pattern`` are ignored. If you want to strip the prefix
+and then do something special, just use ``from_pattern```/``to_pattern``. For
+example, the transformation of ``v1_1_0`` => ``1.1.0`` can be achieved with
+``from_pattern = v(\d+)_(\d+)_(\d+)`` and ``to_pattern = \1.\2.\3``.
+
 Search in a Webpage
 -------------------
 Search through a specific webpage for the version string. This type of version finding has these fields:
diff --git a/nvchecker/get_version.py b/nvchecker/get_version.py
index d0d8489..b4668a8 100644
--- a/nvchecker/get_version.py
+++ b/nvchecker/get_version.py
@@ -17,16 +17,7 @@ handler_precedence = (
 def substitute_version(version, name, conf):
   '''
   Substitute the version string via defined rules in the configuration file.
-  Accepted rules are:
-
-  * from_pattern, to_pattern: Both should be Python regular expressions.
-    `from_pattern` found in the version string will be substituted to
-    `to_pattern`.
-  * prefix: If the version string starts with `prefix`, the prefix is removed.
-    Otherwise the version string is returned as-is.
-
-  If both prefix and from_pattern/to_pattern are used, from_pattern/to_pattern
-  are ignored.
+  See README.rst#global-options for details.
   '''
   prefix = conf.get('prefix')
   if prefix:
diff --git a/tests/test_substitute.py b/tests/test_substitute.py
index d1f8af7..1b033ec 100644
--- a/tests/test_substitute.py
+++ b/tests/test_substitute.py
@@ -15,3 +15,6 @@ async def test_substitute_regex(get_version):
 
 async def test_substitute_regex_missing_ok(get_version):
     assert await get_version("example", {"manual": "r15", "from_pattern": r"r(\d+)([a-z])", "to_pattern": r"r\1.\2"}) == "r15"
+
+async def test_substitute_prefix_has_higher_priority(get_version):
+    assert await get_version("example", {"manual": "r15", "prefix": "r", "from_pattern": "r(\d+)", "to_pattern": "R\1"}) == "15"