diff --git a/CHANGELOG.md b/CHANGELOG.md
index 11f8590..0c68b48 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,8 +1,8 @@
 ## 0.2.0 (2012-06-11)
 
-# Breakpoints.
-* **finish** command.
-* Internal cleanup and bug fixes.
+* Breakpoints
+* **finish** command
+* Internal cleanup and bug fixes
 
 
 ## 0.1.0 (2012-06-07)
diff --git a/lib/pry-debugger/breakpoints.rb b/lib/pry-debugger/breakpoints.rb
index 208f4c0..17d9235 100644
--- a/lib/pry-debugger/breakpoints.rb
+++ b/lib/pry-debugger/breakpoints.rb
@@ -10,13 +10,21 @@ module PryDebugger
 
     # Add a new breakpoint.
     def add(file, line, expression = nil)
-      raise ArgumentError, 'Invalid file!' unless File.exist?(file)
+      if !File.exist?(file) && file != Pry.eval_path
+        raise ArgumentError, 'Invalid file!' unless File.exist?(file)
+      end
+      validate_expression expression
+
       Pry.processor.debugging = true
-      Debugger.add_breakpoint(File.expand_path(file), line, expression)
+
+      path = file == Pry.eval_path ? file : File.expand_path(file)
+      Debugger.add_breakpoint(path, line, expression)
     end
 
     # Change the conditional expression for a breakpoint.
     def change(id, expression = nil)
+      validate_expression expression
+
       breakpoint = find_by_id(id)
       breakpoint.expr = expression
       breakpoint
@@ -79,5 +87,10 @@ module PryDebugger
       breakpoint.enabled = enabled
       breakpoint
     end
+
+    def validate_expression(expression)
+      # `complete_expression?` throws a SyntaxError on invalid input.
+      expression && Pry::Code.complete_expression?(expression)
+    end
   end
 end
diff --git a/lib/pry-debugger/commands.rb b/lib/pry-debugger/commands.rb
index 379da00..05f3ebf 100644
--- a/lib/pry-debugger/commands.rb
+++ b/lib/pry-debugger/commands.rb
@@ -142,13 +142,13 @@ module PryDebugger
 
         file, line =
           case place
-          when /(\d+)/       # Line number only
+          when /^(\d+)$/       # Line number only
             line = $1
             unless PryDebugger.check_file_context(target)
               raise ArgumentError, 'Line number declaration valid only in a file context.'
             end
             [target.eval('__FILE__'), line]
-          when /(.+):(\d+)/  # File and line number
+          when /^(.+):(\d+)$/  # File and line number
             [$1, $2]
           else               # Method or class name
             self.args = [place]
diff --git a/lib/pry-debugger/pry_ext.rb b/lib/pry-debugger/pry_ext.rb
index 4ff9bd3..60ed4f7 100644
--- a/lib/pry-debugger/pry_ext.rb
+++ b/lib/pry-debugger/pry_ext.rb
@@ -2,21 +2,22 @@ require 'pry'
 require 'pry-debugger/processor'
 
 class << Pry
-  alias_method :start_existing, :start
+  alias_method :start_without_pry_debugger, :start
   attr_reader :processor
 
-  def start(target = TOPLEVEL_BINDING, options = {})
+  def start_with_pry_debugger(target = TOPLEVEL_BINDING, options = {})
     @processor ||= PryDebugger::Processor.new
 
     if target.is_a?(Binding) && PryDebugger.check_file_context(target)
       # Wrap the processer around the usual Pry.start to catch navigation
       # commands.
       @processor.run(true) do
-        start_existing(target, options)
+        start_without_pry_debugger(target, options)
       end
     else
       # No need for the tracer unless we have a file context to step through
-      start_existing(target, options)
+      start_without_pry_debugger(target, options)
     end
   end
+  alias_method :start, :start_with_pry_debugger
 end
diff --git a/lib/pry-debugger/pry_remote_ext.rb b/lib/pry-debugger/pry_remote_ext.rb
index 4dbb0f0..709c0af 100644
--- a/lib/pry-debugger/pry_remote_ext.rb
+++ b/lib/pry-debugger/pry_remote_ext.rb
@@ -19,14 +19,15 @@ module PryRemote
     end
 
     # Override to reset our saved global current server session.
-    alias_method :teardown_existing, :teardown
-    def teardown
+    alias_method :teardown_without_pry_debugger, :teardown
+    def teardown_with_pry_debugger
       return if @torn
 
-      teardown_existing
+      teardown_without_pry_debugger
       PryDebugger.current_remote_server = nil
       @torn = true
     end
+    alias_method :teardown, :teardown_with_pry_debugger
   end
 end
 
diff --git a/pry-debugger.gemspec b/pry-debugger.gemspec
index 4a9ec30..d9bfcd4 100644
--- a/pry-debugger.gemspec
+++ b/pry-debugger.gemspec
@@ -20,6 +20,6 @@ Gem::Specification.new do |gem|
   # Dependencies
   gem.required_ruby_version = '>= 1.9.2'
   gem.add_runtime_dependency 'pry', '~> 0.9.9'
-  gem.add_runtime_dependency 'debugger', '~> 1.1.3'
+  gem.add_runtime_dependency 'debugger', '~> 1.2.0'
   gem.add_development_dependency 'pry-remote', '~> 0.1.4'
 end