diff --git a/Dangerfile b/Dangerfile
index 53130cbaa..d09625469 100644
--- a/Dangerfile
+++ b/Dangerfile
@@ -1,2 +1,7 @@
 # Look for prose issues
 prose.lint_files
+
+# Ensure a clean commits history
+if git.commits.any? { |c| c.message =~ /^Merge branch/ }
+  fail('Please rebase to get rid of the merge commits in this PR')
+end