diff --git a/doc/language/character_selectors.rdoc b/doc/language/character_selectors.rdoc
index 20685b8392b655..8bfc9b719b75bf 100644
--- a/doc/language/character_selectors.rdoc
+++ b/doc/language/character_selectors.rdoc
@@ -31,7 +31,6 @@ contained in the selector itself:
   'abracadabra'.delete('abc') # => "rdr"
   '0123456789'.delete('258')  # => "0134679"
   '!@#$%&*()_+'.delete('+&#') # => "!@$%*()_"
-  'тест'.delete('т')          # => "ес"
   'こんにちは'.delete('に')     # => "こんちは"
 
 Note that order and repetitions do not matter:
diff --git a/doc/matchdata/begin.rdoc b/doc/matchdata/begin.rdoc
index 8046dd9d55840c..6100617e19cf0c 100644
--- a/doc/matchdata/begin.rdoc
+++ b/doc/matchdata/begin.rdoc
@@ -10,12 +10,12 @@ returns the offset of the beginning of the <tt>n</tt>th match:
   m[3]       # => "113"
   m.begin(3) # => 3
 
-  m = /(т)(е)(с)/.match('тест')
-  # => #<MatchData "тес" 1:"т" 2:"е" 3:"с">
-  m[0]       # => "тес"
-  m.begin(0) # => 0
-  m[3]       # => "с"
-  m.begin(3) # => 2
+  m = /(ん)(に)(ち)/.match('こんにちは')
+  # => #<MatchData "んにち" 1:"ん" 2:"に" 3:"ち">
+  m[0]       # => "んにち"
+  m.begin(0) # => 1
+  m[3]       # => "ち"
+  m.begin(3) # => 3
 
 When string or symbol argument +name+ is given,
 returns the offset of the beginning for the named match:
diff --git a/doc/matchdata/bytebegin.rdoc b/doc/matchdata/bytebegin.rdoc
index 5b40a7ef73ce4a..54e417a7fca510 100644
--- a/doc/matchdata/bytebegin.rdoc
+++ b/doc/matchdata/bytebegin.rdoc
@@ -10,12 +10,12 @@ returns the offset of the beginning of the <tt>n</tt>th match:
   m[3]       # => "113"
   m.bytebegin(3) # => 3
 
-  m = /(т)(е)(с)/.match('тест')
-  # => #<MatchData "тес" 1:"т" 2:"е" 3:"с">
-  m[0]       # => "тес"
-  m.bytebegin(0) # => 0
-  m[3]       # => "с"
-  m.bytebegin(3) # => 4
+  m = /(ん)(に)(ち)/.match('こんにちは')
+  # => #<MatchData "んにち" 1:"ん" 2:"に" 3:"ち">
+  m[0]           # => "んにち"
+  m.bytebegin(0) # => 3
+  m[3]           # => "ち"
+  m.bytebegin(3) # => 9
 
 When string or symbol argument +name+ is given,
 returns the offset of the beginning for the named match:
diff --git a/doc/matchdata/byteend.rdoc b/doc/matchdata/byteend.rdoc
index eb576640220b05..0a03f762088d22 100644
--- a/doc/matchdata/byteend.rdoc
+++ b/doc/matchdata/byteend.rdoc
@@ -10,12 +10,12 @@ returns the offset of the end of the <tt>n</tt>th match:
   m[3]     # => "113"
   m.byteend(3) # => 6
 
-  m = /(т)(е)(с)/.match('тест')
-  # => #<MatchData "тес" 1:"т" 2:"е" 3:"с">
-  m[0]     # => "тес"
-  m.byteend(0) # => 6
-  m[3]     # => "с"
-  m.byteend(3) # => 6
+  m = /(ん)(に)(ち)/.match('こんにちは')
+  # => #<MatchData "んにち" 1:"ん" 2:"に" 3:"ち">
+  m[0]         # => "んにち"
+  m.byteend(0) # => 12
+  m[3]         # => "ち"
+  m.byteend(3) # => 12
 
 When string or symbol argument +name+ is given,
 returns the offset of the end for the named match:
diff --git a/doc/matchdata/end.rdoc b/doc/matchdata/end.rdoc
index 0209b2d2fc097f..c43a5428f3d1ad 100644
--- a/doc/matchdata/end.rdoc
+++ b/doc/matchdata/end.rdoc
@@ -10,12 +10,12 @@ returns the offset of the end of the <tt>n</tt>th match:
   m[3]     # => "113"
   m.end(3) # => 6
 
-  m = /(т)(е)(с)/.match('тест')
-  # => #<MatchData "тес" 1:"т" 2:"е" 3:"с">
-  m[0]     # => "тес"
-  m.end(0) # => 3
-  m[3]     # => "с"
-  m.end(3) # => 3
+  m = /(ん)(に)(ち)/.match('こんにちは')
+  # => #<MatchData "んにち" 1:"ん" 2:"に" 3:"ち">
+  m[0]     # => "んにち"
+  m.end(0) # => 4
+  m[3]     # => "ち"
+  m.end(3) # => 4
 
 When string or symbol argument +name+ is given,
 returns the offset of the end for the named match:
diff --git a/doc/matchdata/offset.rdoc b/doc/matchdata/offset.rdoc
index 0985316d763de2..4194ef7ef9e13a 100644
--- a/doc/matchdata/offset.rdoc
+++ b/doc/matchdata/offset.rdoc
@@ -11,12 +11,12 @@ returns the starting and ending offsets of the <tt>n</tt>th match:
   m[3]        # => "113"
   m.offset(3) # => [3, 6]
 
-  m = /(т)(е)(с)/.match('тест')
-  # => #<MatchData "тес" 1:"т" 2:"е" 3:"с">
-  m[0]        # => "тес"
-  m.offset(0) # => [0, 3]
-  m[3]        # => "с"
-  m.offset(3) # => [2, 3]
+  m = /(ん)(に)(ち)/.match('こんにちは')
+  # => #<MatchData "んにち" 1:"ん" 2:"に" 3:"ち">
+  m[0]        # => "んにち"
+  m.offset(0) # => [1, 4]
+  m[3]        # => "ち"
+  m.offset(3) # => [3, 4]
 
 When string or symbol argument +name+ is given,
 returns the starting and ending offsets for the named match:
diff --git a/random.c b/random.c
index d902603e98345a..ad7cbca426361c 100644
--- a/random.c
+++ b/random.c
@@ -405,7 +405,7 @@ rand_init(const rb_random_interface_t *rng, rb_random_t *rnd, VALUE seed)
 static VALUE
 random_init(int argc, VALUE *argv, VALUE obj)
 {
-    const rb_random_interface_t *rng;
+    const rb_random_interface_t *rng = NULL;
     rb_random_t *rnd = try_get_rnd(obj, &rng);
 
     if (!rng) {
@@ -1296,7 +1296,7 @@ rand_bytes(const rb_random_interface_t *rng, rb_random_t *rnd, long n)
 static VALUE
 random_bytes(VALUE obj, VALUE len)
 {
-    const rb_random_interface_t *rng;
+    const rb_random_interface_t *rng = NULL;
     rb_random_t *rnd = try_get_rnd(obj, &rng);
     return rand_bytes(rng, rnd, NUM2LONG(rb_to_int(len)));
 }
@@ -1570,7 +1570,7 @@ static VALUE rand_random(int argc, VALUE *argv, VALUE obj, const rb_random_inter
 static VALUE
 random_rand(int argc, VALUE *argv, VALUE obj)
 {
-    const rb_random_interface_t *rng;
+    const rb_random_interface_t *rng = NULL;
     rb_random_t *rnd = try_get_rnd(obj, &rng);
     VALUE v = rand_random(argc, argv, obj, rng, rnd);
     check_random_number(v, argv);
@@ -1621,7 +1621,7 @@ rand_random(int argc, VALUE *argv, VALUE obj, const rb_random_interface_t *rng,
 static VALUE
 rand_random_number(int argc, VALUE *argv, VALUE obj)
 {
-    const rb_random_interface_t *rng;
+    const rb_random_interface_t *rng = NULL;
     rb_random_t *rnd = try_get_rnd(obj, &rng);
     VALUE v = rand_random(argc, argv, obj, rng, rnd);
     if (NIL_P(v)) v = rand_random(0, 0, obj, rng, rnd);