diff --git a/ChangeLog b/ChangeLog
index 0c22cfcdbf..3cda6e3ce7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Dec 26 06:35:25 2013  Marc-Andre Lafortune  <ruby-core@marc-andre.ca>
+
+	* proc.c: Having any mandatory keyword argument increases min arity
+	  [#9299]
+
 Thu Dec 26 06:27:08 2013  Marc-Andre Lafortune  <ruby-core@marc-andre.ca>
 
 	* proc.c: Having optional keyword arguments makes maximum arity +1,
diff --git a/proc.c b/proc.c
index 82f9e38ff2..1b61d71ac1 100644
--- a/proc.c
+++ b/proc.c
@@ -881,7 +881,7 @@ rb_iseq_min_max_arity(const rb_iseq_t *iseq, int *max)
 	iseq->argc + iseq->arg_post_len + iseq->arg_opts -
 	(iseq->arg_opts > 0) + (iseq->arg_keyword != -1)
       : UNLIMITED_ARGUMENTS;
-    return iseq->argc + iseq->arg_post_len;
+    return iseq->argc + iseq->arg_post_len + (iseq->arg_keyword_required > 0);
 }
 
 static int
diff --git a/test/ruby/test_proc.rb b/test/ruby/test_proc.rb
index 6c92f1e374..1c8a053cca 100644
--- a/test/ruby/test_proc.rb
+++ b/test/ruby/test_proc.rb
@@ -85,6 +85,11 @@ class TestProc < Test::Unit::TestCase
     assert_equal(2, proc{|x, y=0, z, **o|}.arity)
     assert_equal(-3, proc{|x, y=0, *z, w, **o|}.arity)
 
+    assert_equal(2, proc{|x, y=0, z, a:1|}.arity)
+    assert_equal(3, proc{|x, y=0, z, a:|}.arity)
+    assert_equal(-4, proc{|x, y, *rest, a:, b:, c:|}.arity)
+    assert_equal(3, proc{|x, y=0, z, a:, **o|}.arity)
+
     assert_equal(0, lambda{}.arity)
     assert_equal(0, lambda{||}.arity)
     assert_equal(1, lambda{|x|}.arity)