diff --git a/CHANGELOG.md b/CHANGELOG.md
index a247452..bb9ecb1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## 1.5.0
 
+  * Deprecate `seqSpine`. Changes in version 1.4.2.0 made it useless.
+
   * Add pattern synonyms to work with `MinQueue` and `MinPQueue`.
     ([#92](http://github.com/lspitzner/pqueue/pull/92))
 
diff --git a/src/Data/PQueue/Internals.hs b/src/Data/PQueue/Internals.hs
index f2b742d..0d27807 100644
--- a/src/Data/PQueue/Internals.hs
+++ b/src/Data/PQueue/Internals.hs
@@ -343,9 +343,10 @@ toListUApp (MinQueue _ x ts) app = x : BQ.foldrU (:) app ts
 --
 -- Note: The spine of a 'MinQueue' is stored somewhat lazily. Most operations
 -- take great care to prevent chains of thunks from accumulating along the
--- spine to the detriment of performance. However, @mapU@ can leave expensive
--- thunks in the structure and repeated applications of that function can
--- create thunk chains.
+-- spine to the detriment of performance. The only one that doesn't,
+-- 'mapU', does not benefit from forcing the spine anyway. Forcing the spine
+-- of the result just forces the creation of thunks for all the elements.
+{-# DEPRECATED seqSpine "This function is no longer useful." #-}
 seqSpine :: MinQueue a -> b -> b
 seqSpine Empty z = z
 seqSpine (MinQueue _ _ ts) z = BQ.seqSpine ts z
diff --git a/src/Data/PQueue/Max.hs b/src/Data/PQueue/Max.hs
index 6a81739..45b80c8 100644
--- a/src/Data/PQueue/Max.hs
+++ b/src/Data/PQueue/Max.hs
@@ -371,8 +371,9 @@ keysQueue (Prio.MaxPQ q) = MaxQ (Min.keysQueue q)
 --
 -- Note: The spine of a 'MaxQueue' is stored somewhat lazily. Most operations
 -- take great care to prevent chains of thunks from accumulating along the
--- spine to the detriment of performance. However, 'mapU' can leave expensive
--- thunks in the structure and repeated applications of that function can
--- create thunk chains.
+-- spine to the detriment of performance. The only one that doesn't,
+-- 'mapU', does not benefit from forcing the spine anyway. Forcing the spine
+-- of the result just forces the creation of thunks for all the elements.
+{-# DEPRECATED seqSpine "This function is no longer useful." #-}
 seqSpine :: MaxQueue a -> b -> b
 seqSpine (MaxQ q) = Min.seqSpine q
diff --git a/src/Data/PQueue/Prio/Internals.hs b/src/Data/PQueue/Prio/Internals.hs
index 131ec9d..871a21a 100644
--- a/src/Data/PQueue/Prio/Internals.hs
+++ b/src/Data/PQueue/Prio/Internals.hs
@@ -758,9 +758,11 @@ mapKeysMonoF f fCh ts0 = case ts0 of
 --
 -- Note: The spine of a 'MinPQueue' is stored somewhat lazily. Most operations
 -- take great care to prevent chains of thunks from accumulating along the
--- spine to the detriment of performance. However, 'mapKeysMonotonic' can leave
--- expensive thunks in the structure and repeated applications of that function
--- can create thunk chains.
+-- spine to the detriment of performance. The only ones that don't,
+-- 'mapKeysMonotonic', 'mapWithKey', 'traverseWithKey', etc., do not benefit
+-- from forcing the spine anyway. Forcing the spine just forces the creation
+-- of thunks for all the elements.
+{-# DEPRECATED seqSpine "This function is no longer useful." #-}
 seqSpine :: MinPQueue k a -> b -> b
 seqSpine Empty z0 = z0
 seqSpine (MinPQ _ _ _ ts0) z0 = ts0 `seqSpineF` z0 where
diff --git a/src/Data/PQueue/Prio/Max/Internals.hs b/src/Data/PQueue/Prio/Max/Internals.hs
index 701bb28..d7bcc5b 100644
--- a/src/Data/PQueue/Prio/Max/Internals.hs
+++ b/src/Data/PQueue/Prio/Max/Internals.hs
@@ -577,10 +577,12 @@ toListU (MaxPQ q) = fmap (first' unDown) (Q.toListU q)
 
 -- | \(O(\log n)\). @seqSpine q r@ forces the spine of @q@ and returns @r@.
 --
--- Note: The spine of a 'MaxPQueue' is stored somewhat lazily. Most operations
+-- Note: The spine of a 'MinPQueue' is stored somewhat lazily. Most operations
 -- take great care to prevent chains of thunks from accumulating along the
--- spine to the detriment of performance. However, 'mapKeysMonotonic' can leave
--- expensive thunks in the structure and repeated applications of that function
--- can create thunk chains.
+-- spine to the detriment of performance. The only ones that don't,
+-- 'mapKeysMonotonic', 'mapWithKey', 'traverseWithKey', etc., do not benefit
+-- from forcing the spine anyway. Forcing the spine just forces the creation
+-- of thunks for all the elements.
+{-# DEPRECATED seqSpine "This function is no longer useful." #-}
 seqSpine :: MaxPQueue k a -> b -> b
 seqSpine (MaxPQ q) = Q.seqSpine q