diff --git a/lib/oga.rb b/lib/oga.rb
index 089a43a..d87cc87 100644
--- a/lib/oga.rb
+++ b/lib/oga.rb
@@ -55,6 +55,7 @@ require 'oga/ruby/generator'
 
 require 'oga/xpath/lexer'
 require 'oga/xpath/parser'
+require 'oga/xpath/context'
 require 'oga/xpath/compiler'
 require 'oga/xpath/conversion'
 
diff --git a/lib/oga/xpath/compiler.rb b/lib/oga/xpath/compiler.rb
index a0a4eca..2fc22cf 100644
--- a/lib/oga/xpath/compiler.rb
+++ b/lib/oga/xpath/compiler.rb
@@ -12,6 +12,11 @@ module Oga
       # @return [Oga::LRU]
       CACHE = LRU.new
 
+      # Context for compiled Procs. As compiled Procs do not mutate the
+      # enclosing environment we can just re-use the same instance without
+      # synchronization.
+      CONTEXT = Context.new
+
       # Wildcard for node names/namespace prefixes.
       STAR = '*'
 
@@ -86,7 +91,7 @@ module Oga
         generator = Ruby::Generator.new
         source    = generator.process(proc_ast)
 
-        eval(source)
+        CONTEXT.evaluate(source)
       ensure
         reset
       end
diff --git a/lib/oga/xpath/context.rb b/lib/oga/xpath/context.rb
new file mode 100644
index 0000000..59834c8
--- /dev/null
+++ b/lib/oga/xpath/context.rb
@@ -0,0 +1,17 @@
+module Oga
+  module XPath
+    # Class used as the context for compiled XPath Procs.
+    #
+    # The binding of this class is used for the binding of Procs compiled by
+    # {Compiler}. Not using a specific binding would result in the procs
+    # using the binding of {Compiler#compile}, which could lead to race
+    # conditions.
+    class Context
+      # @param [String] string
+      # @return [Proc]
+      def evaluate(string)
+        binding.eval(string)
+      end
+    end # Context
+  end # XPath
+end # Oga
diff --git a/spec/oga/xpath/compiler_spec.rb b/spec/oga/xpath/compiler_spec.rb
index 0d690ce..d982672 100644
--- a/spec/oga/xpath/compiler_spec.rb
+++ b/spec/oga/xpath/compiler_spec.rb
@@ -49,5 +49,27 @@ describe Oga::XPath::Compiler do
         block.call(doc).should be_an_instance_of(Oga::XML::NodeSet)
       end
     end
+
+    # This test relies on Binding#receiver (Binding#self on Rubinius), which
+    # sadly isn't available on all tested Ruby versions.
+    #
+    # Procs should have their own Binding as otherwise concurrent usage could
+    # lead to race conditions due to variable scopes and such being re-used.
+    [:receiver, :self].each do |binding_method|
+      if Binding.method_defined?(binding_method)
+        describe 'the returned Proc' do
+          it 'uses an isolated Binding' do
+            ast   = parse_xpath('foo')
+            block = @compiler.compile(ast)
+
+            binding_context = block.binding.send(binding_method)
+
+            binding_context.should be_an_instance_of(Oga::XPath::Context)
+          end
+        end
+
+        break
+      end
+    end
   end
 end
diff --git a/spec/oga/xpath/context_spec.rb b/spec/oga/xpath/context_spec.rb
new file mode 100644
index 0000000..6c9ca98
--- /dev/null
+++ b/spec/oga/xpath/context_spec.rb
@@ -0,0 +1,23 @@
+require 'spec_helper'
+
+describe Oga::XPath::Context do
+  describe '#evaluate' do
+    it 'returns the result of eval()' do
+      context = described_class.new
+
+      context.evaluate('10').should == 10
+    end
+
+    describe 'assigning a variable in a lambda' do
+      it 'assigns the variable locally to the lambda' do
+        context = described_class.new
+
+        block = context.evaluate('lambda { number = 10 }')
+
+        block.call
+
+        expect { context.evaluate('number') }.to raise_error(NameError)
+      end
+    end
+  end
+end