diff --git a/Mathlib/Tactic/Linter/ValidatePRTitle.lean b/Mathlib/Tactic/Linter/ValidatePRTitle.lean
index 1fb45d557e4a16..478e2e9bf94488 100644
--- a/Mathlib/Tactic/Linter/ValidatePRTitle.lean
+++ b/Mathlib/Tactic/Linter/ValidatePRTitle.lean
@@ -119,17 +119,9 @@ public def validateTitle (title : String) : Array String := Id.run do
       -- Future: we could check if `scope` describes a directory that actually exist.
       -- Should we allow special syntax such as `Data/*/Basic` or `{Set,Group}Theory`?
 
-    -- Titles should be lower-cased (but we allow abbreviations, or a `s` or `'ed` suffix).
-    if subject.front.toLower != subject.front then
-      let firstWord := subject.takeWhile (!·.isWhitespace)
-      let suffixes := ["'s", "s", "'ed"]
-      let mut withoutSuffix := firstWord
-      for suff in suffixes do
-        if firstWord.endsWith suff then
-          withoutSuffix := firstWord.dropSuffix suff
-          break
-      if !(isAbbreviation withoutSuffix) then
-        errors := errors.push s!"error: the PR subject `{subject}` should be lowercased"
+    -- note: we do not check capitalisation as the subject might start with abbreviations or
+    -- proper nouns.
+
     if subject.endsWith "." then
       errors := errors.push "error: the PR title should not end with a full stop"
     else if subject.endsWith " " then
diff --git a/MathlibTest/ValidatePRTitle.lean b/MathlibTest/ValidatePRTitle.lean
index d7b20b55b20290..c20980f5058734 100644
--- a/MathlibTest/ValidatePRTitle.lean
+++ b/MathlibTest/ValidatePRTitle.lean
@@ -114,38 +114,6 @@ section subject
 #guard_msgs in
 #check_title "feat: bad title."
 
-/-- info: Message: 'error: the PR subject `My Bad Title` should be lowercased' -/
-#guard_msgs in
-#check_title "feat: My Bad Title"
--- Starting with an acronym is fine, however.
-#guard_msgs in
-#check_title "feat: RPC acronyms are fine"
-#guard_msgs in #check_title "feat: `ℕ` is countable"
--- We also allow a `s`, `'s` or `'ed` suffix, as manual heuristic.
-#guard_msgs in #check_title "feat: RPCs are yellow"
-#guard_msgs in #check_title "chore: LLMs require adjusting our policies"
-#guard_msgs in #check_title "chore: PR'ed lemmas"
-#guard_msgs in #check_title "feat(CI): PR's to be deleted"
-#guard_msgs in #check_title "chore: FCP'ed decisions should be listed separately"
--- We only remove at most one suffix.
-/-- info: Message: 'error: the PR subject `PR'ed's lemmas` should be lowercased' -/
-#guard_msgs in #check_title "chore: PR'ed's lemmas"
-/-- info: Message: 'error: the PR subject `PRs's something` should be lowercased' -/
-#guard_msgs in #check_title "chore: PRs's something"
--- This is not quite an abbreviation (and a grammar error).
-/--
-info: Message: 'error: the PR subject `FCPed decisions should be listed separately` should be lowercased'
--/
-#guard_msgs in #check_title "chore: FCPed decisions should be listed separately"
-
--- This PR title is arguably not very bad (Lindelöf is a proper name),
--- a better fix is to start with a verb (which you should do anyway.)
-/--
-info: Message: 'error: the PR subject `Lindelöf spaces something something` should be lowercased'
--/
-#guard_msgs in
-#check_title "feat: Lindelöf spaces something something"
-
 #guard_msgs in
 #check_title "feat: add lemmas about Lindelöf spaces"
 
@@ -215,13 +183,5 @@ info: Message: 'error: the PR title contains multiple consecutive spaces; please
 #guard_msgs in
 #check_title "feat(ModuleForm): 2e is less than 6"
 
-/-- info: Message: 'error: the PR subject `W3c` should be lowercased' -/
-#guard_msgs in
-#check_title "feat(ModuleForm): W3c"
-
 #guard_msgs in
 #check_title "feat(ModuleForm): W3C"
-
-/-- info: Message: 'error: the PR subject `A new lemma` should be lowercased' -/
-#guard_msgs in
-#check_title "feat(ModuleForm): A new lemma"