diff --git a/lib/mspec/guards/block_device.rb b/lib/mspec/guards/block_device.rb
index 0dc252e3..f33333f7 100644
--- a/lib/mspec/guards/block_device.rb
+++ b/lib/mspec/guards/block_device.rb
@@ -2,8 +2,12 @@
 
 class BlockDeviceGuard < SpecGuard
   def match?
-    block = `find /dev /devices -type b 2> /dev/null`
-    !(block.nil? || block.empty?)
+    platform_is_not :freebsd, :windows do
+      block = `find /dev /devices -type b 2> /dev/null`
+      return !(block.nil? || block.empty?)
+    end
+
+    false
   end
 end
 
diff --git a/spec/guards/block_device_spec.rb b/spec/guards/block_device_spec.rb
index 44fb9fa3..2d748e9f 100644
--- a/spec/guards/block_device_spec.rb
+++ b/spec/guards/block_device_spec.rb
@@ -9,16 +9,26 @@
     BlockDeviceGuard.stub!(:new).and_return(@guard)
   end
 
-  it "yields if block device is available" do
-    @guard.should_receive(:`).and_return("block devices")
-    with_block_device { ScratchPad.record :yield }
-    ScratchPad.recorded.should == :yield
+  platform_is_not :freebsd, :windows do
+    it "yields if block device is available" do
+      @guard.should_receive(:`).and_return("block devices")
+      with_block_device { ScratchPad.record :yield }
+      ScratchPad.recorded.should == :yield
+    end
+
+    it "does not yield if block device is not available" do
+      @guard.should_receive(:`).and_return(nil)
+      with_block_device { ScratchPad.record :yield }
+      ScratchPad.recorded.should_not == :yield
+    end
   end
 
-  it "does not yield if block device is not available" do
-    @guard.should_receive(:`).and_return(nil)
-    with_block_device { ScratchPad.record :yield }
-    ScratchPad.recorded.should_not == :yield
+  platform_is :freebsd, :windows do
+    it "does not yield, since platform does not support block devices" do
+      @guard.should_not_receive(:`)
+      with_block_device { ScratchPad.record :yield }
+      ScratchPad.recorded.should_not == :yield
+    end
   end
 
   it "sets the name of the guard to :with_block_device" do