4 files changed, 17 insertions, 3 deletions
diff --git a/mrbgems/mruby-proc-ext/mrblib/proc.rb b/mrbgems/mruby-proc-ext/mrblib/proc.rb
index 5dd9981df..b71663938 100644
--- a/mrbgems/mruby-proc-ext/mrblib/proc.rb
+++ b/mrbgems/mruby-proc-ext/mrblib/proc.rb
@@ -13,9 +13,11 @@ class Proc
   end
 
   def curry(arity=self.arity)
+    type = :proc
     abs = lambda {|a| a < 0 ? -a - 1 : a}
     arity = abs[arity]
     if lambda?
+      type = :lambda
       self_arity = self.arity
       if (self_arity >= 0 && arity != self_arity) ||
          (self_arity < 0 && abs[self_arity] > arity)
@@ -25,7 +27,7 @@ class Proc
 
     pproc = self
     make_curry = proc do |given_args=[]|
-      proc do |*args|
+      send(type) do |*args|
         new_args = given_args + args
         if new_args.size >= arity
           pproc[*new_args]
diff --git a/mrbgems/mruby-proc-ext/test/proc.rb b/mrbgems/mruby-proc-ext/test/proc.rb
index bca9b463a..75e11dd93 100644
--- a/mrbgems/mruby-proc-ext/test/proc.rb
+++ b/mrbgems/mruby-proc-ext/test/proc.rb
@@ -41,6 +41,9 @@ assert('Proc#curry') do
   assert_raise(ArgumentError) { b.curry[1, 2][3, 4] }
   assert_raise(ArgumentError) { b.curry(5) }
   assert_raise(ArgumentError) { b.curry(1) }
+
+  assert_false(proc{}.curry.lambda?)
+  assert_true(lambda{}.curry.lambda?)
 end
 
 assert('Proc#parameters') do
diff --git a/src/proc.c b/src/proc.c
index 4cb9ffe18..f98998f68 100644
--- a/src/proc.c
+++ b/src/proc.c
@@ -200,7 +200,7 @@ mrb_proc_arity(mrb_state *mrb, mrb_value self)
   struct RProc *p = mrb_proc_ptr(self);
   mrb_code *iseq = mrb_proc_iseq(mrb, p);
   mrb_aspec aspec;
-  int ma, ra, pa, arity;
+  int ma, op, ra, pa, arity;
 
   if (MRB_PROC_CFUNC_P(p)) {
     /* TODO cfunc aspec not implemented yet */
@@ -214,9 +214,10 @@ mrb_proc_arity(mrb_state *mrb, mrb_value self)
 
   aspec = GETARG_Ax(*iseq);
   ma = MRB_ASPEC_REQ(aspec);
+  op = MRB_ASPEC_OPT(aspec);
   ra = MRB_ASPEC_REST(aspec);
   pa = MRB_ASPEC_POST(aspec);
-  arity = ra ? -(ma + pa + 1) : ma + pa;
+  arity = ra || (MRB_PROC_STRICT_P(p) && op) ? -(ma + pa + 1) : ma + pa;
 
   return mrb_fixnum_value(arity);
 }
diff --git a/test/t/proc.rb b/test/t/proc.rb
index 22ccceb68..888b7d56a 100644
--- a/test/t/proc.rb
+++ b/test/t/proc.rb
@@ -36,6 +36,14 @@ assert('Proc#arity', '15.2.17.4.2') do
   assert_equal(-3, b)
   assert_equal  1, c
   assert_equal  1, d
+
+  e = ->(x=0, y){}.arity
+  f = ->((x, y), z=0){}.arity
+  g = ->(x=0){}.arity
+
+  assert_equal(-2, e)
+  assert_equal(-2, f)
+  assert_equal(-1, g)
 end
 
 assert('Proc#call', '15.2.17.4.3') do