diff --git a/Gemfile b/Gemfile
index 3672ecd7..3ec88871 100644
--- a/Gemfile
+++ b/Gemfile
@@ -12,7 +12,7 @@ gem "rake", "~> 13.0"
 gem "require_all"
 gem "sensible_logging", "~> 0.4.7"
 gem "sentry-raven"
-gem "sequel", "~> 5.61"
+gem "sequel", "~> 5.78"
 gem "sinatra"
 
 group :test do
diff --git a/Gemfile.lock b/Gemfile.lock
index d3d74deb..6f62dcfa 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -179,7 +179,8 @@ GEM
       rack (>= 2, < 4)
     sentry-raven (3.1.2)
       faraday (>= 1.0)
-    sequel (5.61.0)
+    sequel (5.78.0)
+      bigdecimal
     shellany (0.0.1)
     simplecov (0.22.0)
       docile (~> 1.1)
@@ -225,7 +226,7 @@ DEPENDENCIES
   rubocop-govuk
   sensible_logging (~> 0.4.7)
   sentry-raven
-  sequel (~> 5.61)
+  sequel (~> 5.78)
   simplecov
   sinatra
   timecop