diff --git a/CHANGELOG.md b/CHANGELOG.md
index d0a70162..02c229a9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@
 ### Changes
 
 * [#193](https://github.com/mmozuras/pronto/issues/193): rename `pronto run --index` option to `--unstaged`.
+* [#49](https://github.com/mmozuras/pronto/issues/49): Handle non-existance of GitHub pull requests gracefully
 
 ## 0.8.2
 
diff --git a/lib/pronto.rb b/lib/pronto.rb
index 91e1afb1..eda645ac 100644
--- a/lib/pronto.rb
+++ b/lib/pronto.rb
@@ -5,6 +5,8 @@
 require 'httparty'
 require 'rainbow'
 
+require 'pronto/error'
+
 require 'pronto/gem_names'
 
 require 'pronto/logger'
diff --git a/lib/pronto/cli.rb b/lib/pronto/cli.rb
index dc16f74b..39318a66 100644
--- a/lib/pronto/cli.rb
+++ b/lib/pronto/cli.rb
@@ -66,6 +66,8 @@ def run(path = nil)
       end
     rescue Rugged::RepositoryError
       puts '"pronto" should be run from a git repository'
+    rescue Pronto::Error => e
+      $stderr.puts "Pronto errored: #{e.message}"
     end
 
     desc 'list', 'Lists pronto runners that are available to be used'
diff --git a/lib/pronto/error.rb b/lib/pronto/error.rb
new file mode 100644
index 00000000..d6a7cb5a
--- /dev/null
+++ b/lib/pronto/error.rb
@@ -0,0 +1,3 @@
+module Pronto
+  class Error < StandardError; end
+end
diff --git a/lib/pronto/github.rb b/lib/pronto/github.rb
index c1138381..e7352b61 100644
--- a/lib/pronto/github.rb
+++ b/lib/pronto/github.rb
@@ -7,6 +7,10 @@ def pull_comments(sha)
                       comment.position || comment.original_position)
         end
       end
+    rescue Octokit::NotFound => e
+      @config.logger.log("Error raised and rescued: #{e}")
+      msg = "Pull request for sha #{sha} with id #{pull_id} was not found."
+      raise Pronto::Error, msg
     end
 
     def commit_comments(sha)
diff --git a/spec/pronto/github_spec.rb b/spec/pronto/github_spec.rb
index e6d45486..afe4af4d 100644
--- a/spec/pronto/github_spec.rb
+++ b/spec/pronto/github_spec.rb
@@ -66,6 +66,16 @@ module Pronto
           subject
         end
       end
+
+      context 'pull request does not exist' do
+        specify do
+          Octokit::Client.any_instance
+            .should_receive(:pull_comments)
+            .and_raise(Octokit::NotFound)
+
+          -> { subject }.should raise_error(Pronto::Error)
+        end
+      end
     end
 
     describe '#create_commit_status' do