diff --git a/ouroboros-consensus/changelog.d/20240829_095937_alexander.esgen_gdd_splitAtSlot.md b/ouroboros-consensus/changelog.d/20240829_095937_alexander.esgen_gdd_splitAtSlot.md
new file mode 100644
index 0000000000..ab905699d0
--- /dev/null
+++ b/ouroboros-consensus/changelog.d/20240829_095937_alexander.esgen_gdd_splitAtSlot.md
@@ -0,0 +1,3 @@
+### Patch
+
+- Used new `AF.splitAtSlot` function in GDD.
diff --git a/ouroboros-consensus/src/ouroboros-consensus/Ouroboros/Consensus/Genesis/Governor.hs b/ouroboros-consensus/src/ouroboros-consensus/Ouroboros/Consensus/Genesis/Governor.hs
index 4edbc85b9d..6c273015a4 100644
--- a/ouroboros-consensus/src/ouroboros-consensus/Ouroboros/Consensus/Genesis/Governor.hs
+++ b/ouroboros-consensus/src/ouroboros-consensus/Ouroboros/Consensus/Genesis/Governor.hs
@@ -402,8 +402,7 @@ densityDisconnect (GenesisWindow sgen) (SecurityParam k) states candidateSuffixe
 
     -- This is performance sensitive. We used to call @takeWhileOldest@ here,
     -- which would reconstruct much of the original fragment.
-    dropBeyondGenesisWindow =
-      AF.dropWhileNewest ((>= firstSlotAfterGenesisWindow) . blockSlot)
+    dropBeyondGenesisWindow = AF.splitAtSlot firstSlotAfterGenesisWindow
 
 -- Note [Chain disagreement]
 -- ~~~~~~~~~~~~~~~~~~~~~~~~~