diff --git a/library/fiber/alive_spec.rb b/core/fiber/alive_spec.rb
similarity index 98%
rename from library/fiber/alive_spec.rb
rename to core/fiber/alive_spec.rb
index 47149d5279..a1df582435 100644
--- a/library/fiber/alive_spec.rb
+++ b/core/fiber/alive_spec.rb
@@ -1,7 +1,5 @@
 require_relative '../../spec_helper'
 
-require 'fiber'
-
 describe "Fiber#alive?" do
   it "returns true for a Fiber that hasn't had #resume called" do
     fiber = Fiber.new { true }
diff --git a/core/fiber/blocking_spec.rb b/core/fiber/blocking_spec.rb
index ebefa116af..ed3c057516 100644
--- a/core/fiber/blocking_spec.rb
+++ b/core/fiber/blocking_spec.rb
@@ -1,8 +1,6 @@
 require_relative '../../spec_helper'
 require_relative 'shared/blocking'
 
-require "fiber"
-
 describe "Fiber.blocking?" do
   it_behaves_like :non_blocking_fiber, -> { Fiber.blocking? }
 
diff --git a/library/fiber/current_spec.rb b/core/fiber/current_spec.rb
similarity index 86%
rename from library/fiber/current_spec.rb
rename to core/fiber/current_spec.rb
index 66e7b35167..b93df77a89 100644
--- a/library/fiber/current_spec.rb
+++ b/core/fiber/current_spec.rb
@@ -1,12 +1,6 @@
 require_relative '../../spec_helper'
 
-require 'fiber'
-
 describe "Fiber.current" do
-  it "is available without an extra require" do
-    ruby_exe("print Fiber.current.class", options: '--disable-gems --disable-did-you-mean').should == "Fiber"
-  end
-
   it "returns the root Fiber when called outside of a Fiber" do
     root = Fiber.current
     root.should be_an_instance_of(Fiber)
diff --git a/core/fiber/inspect_spec.rb b/core/fiber/inspect_spec.rb
index f20a153fc2..fcfef20716 100644
--- a/core/fiber/inspect_spec.rb
+++ b/core/fiber/inspect_spec.rb
@@ -1,5 +1,4 @@
 require_relative '../../spec_helper'
-require 'fiber'
 
 describe "Fiber#inspect" do
   describe "status" do
diff --git a/core/fiber/raise_spec.rb b/core/fiber/raise_spec.rb
index 2f2baa4a12..124f56fe7d 100644
--- a/core/fiber/raise_spec.rb
+++ b/core/fiber/raise_spec.rb
@@ -130,7 +130,6 @@
 
 describe "Fiber#raise" do
   it "transfers and raises on a transferring fiber" do
-    require "fiber"
     root = Fiber.current
     fiber = Fiber.new { root.transfer }
     fiber.transfer
diff --git a/core/fiber/resume_spec.rb b/core/fiber/resume_spec.rb
index ab9a6799ab..4b20f4b4bf 100644
--- a/core/fiber/resume_spec.rb
+++ b/core/fiber/resume_spec.rb
@@ -1,5 +1,5 @@
 require_relative '../../spec_helper'
-require_relative '../../shared/fiber/resume'
+require_relative 'shared/resume'
 
 describe "Fiber#resume" do
   it_behaves_like :fiber_resume, :resume
@@ -67,4 +67,17 @@
 
     ruby_exe(code).should == "ensure executed\n"
   end
+
+  it "can work with Fiber#transfer" do
+    fiber1 = Fiber.new { true }
+    fiber2 = Fiber.new { fiber1.transfer; Fiber.yield 10 ; Fiber.yield 20; raise }
+    fiber2.resume.should == 10
+    fiber2.resume.should == 20
+  end
+
+  it "raises a FiberError if the Fiber attempts to resume a resuming fiber" do
+    root_fiber = Fiber.current
+    fiber1 = Fiber.new { root_fiber.resume }
+    -> { fiber1.resume }.should raise_error(FiberError, /attempt to resume a resuming fiber/)
+  end
 end
diff --git a/shared/fiber/resume.rb b/core/fiber/shared/resume.rb
similarity index 100%
rename from shared/fiber/resume.rb
rename to core/fiber/shared/resume.rb
diff --git a/library/fiber/transfer_spec.rb b/core/fiber/transfer_spec.rb
similarity index 97%
rename from library/fiber/transfer_spec.rb
rename to core/fiber/transfer_spec.rb
index e20d51352e..238721475d 100644
--- a/library/fiber/transfer_spec.rb
+++ b/core/fiber/transfer_spec.rb
@@ -1,7 +1,5 @@
 require_relative '../../spec_helper'
-require_relative '../../shared/fiber/resume'
-
-require 'fiber'
+require_relative 'shared/resume'
 
 describe "Fiber#transfer" do
   it_behaves_like :fiber_resume, :transfer
diff --git a/library/fiber/resume_spec.rb b/library/fiber/resume_spec.rb
deleted file mode 100644
index fd69d3ba99..0000000000
--- a/library/fiber/resume_spec.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_relative '../../spec_helper'
-
-require 'fiber'
-
-describe "Fiber#resume" do
-  it "can work with Fiber#transfer" do
-    fiber1 = Fiber.new { true }
-    fiber2 = Fiber.new { fiber1.transfer; Fiber.yield 10 ; Fiber.yield 20; raise }
-    fiber2.resume.should == 10
-    fiber2.resume.should == 20
-  end
-
-  it "raises a FiberError if the Fiber attempts to resume a resuming fiber" do
-    root_fiber = Fiber.current
-    fiber1 = Fiber.new { root_fiber.resume }
-    -> { fiber1.resume }.should raise_error(FiberError, /attempt to resume a resuming fiber/)
-  end
-end
diff --git a/optional/capi/fiber_spec.rb b/optional/capi/fiber_spec.rb
index 6c72869106..05d867498c 100644
--- a/optional/capi/fiber_spec.rb
+++ b/optional/capi/fiber_spec.rb
@@ -1,5 +1,4 @@
 require_relative 'spec_helper'
-require 'fiber'
 
 load_extension('fiber')