diff --git a/extra/chromium/PKGBUILD b/extra/chromium/PKGBUILD
index e4bac7307..26dad70f5 100644
--- a/extra/chromium/PKGBUILD
+++ b/extra/chromium/PKGBUILD
@@ -16,7 +16,7 @@ highmem=1
 
 pkgname=chromium
 pkgver=86.0.4240.111
-pkgrel=1
+pkgrel=2
 _launcher_ver=6
 _gcc_patchset=6
 pkgdesc="A web browser built for speed, simplicity, and security"
@@ -42,6 +42,7 @@ source=(https://commondatastorage.googleapis.com/chromium-browser-official/$pkgn
         only-fall-back-to-the-i965-driver-if-we-re-on-iHD.patch
         remove-dead-reloc-in-nonalloc-LD-flags.patch
         check-for-enable-accelerated-video-decode-on-Linux.patch
+        xproto-fix-underflow-in-Fp1616ToDouble.patch
         chromium-skia-harmony.patch
         0001-crashpad-include-limits.patch
         chromium-81.0.4044.122-Fix-sandbox-Aw-snap-for-syscalls-403-and-407.patch)
@@ -52,6 +53,7 @@ sha256sums=('f27bdb02ebf3c48abe054c73f1ae57e22a22535ea34f5edf8693ab8432a7c717'
             '7514c6c81a64a5457b66494a366fbb39005563eecc48d1a39033dd06aec4e300'
             '7cace84d7494190e7882d3e637820646ec8d64808f0a2128c515bd44991a3790'
             '03d03a39b2afa40083eb8ccb9616a51619f71da92348effc8ee289cbda10128b'
+            '1ec617b362bf97cce4254debd04d8396f17dec0ae1071b52ec8c1c3d86dbd322'
             '771292942c0901092a402cc60ee883877a99fb804cb54d568c8c6c94565a48e1'
             'df99f49ad58b70c9a3e1827d7e80b62e4363419334ed83373cf55b79c17b6f10'
             '4837f797a910795bf3161805a3302d5f3701573ca90da8af32b2f4aa62510d20')
@@ -118,6 +120,7 @@ prepare() {
   patch -Np1 -i ../only-fall-back-to-the-i965-driver-if-we-re-on-iHD.patch
   patch -Np1 -i ../remove-dead-reloc-in-nonalloc-LD-flags.patch
   patch -Np1 -i ../check-for-enable-accelerated-video-decode-on-Linux.patch
+  patch -Np1 -i ../xproto-fix-underflow-in-Fp1616ToDouble.patch
 
   # Fixes for building with libstdc++ instead of libc++
   patch -Np1 -i ../patches/chromium-86-nearby-include.patch
diff --git a/extra/chromium/xproto-fix-underflow-in-Fp1616ToDouble.patch b/extra/chromium/xproto-fix-underflow-in-Fp1616ToDouble.patch
new file mode 100644
index 000000000..8fcbd7226
--- /dev/null
+++ b/extra/chromium/xproto-fix-underflow-in-Fp1616ToDouble.patch
@@ -0,0 +1,37 @@
+From 5ade494a9966c7a9675af86dc42aca62fb4d806d Mon Sep 17 00:00:00 2001
+From: Tom Anderson <thomasanderson@chromium.org>
+Date: Wed, 21 Oct 2020 22:02:35 +0000
+Subject: [PATCH] [XProto] Fix underflow in Fp1616ToDouble
+
+x11::Input::Fp1616 should be treated as a signed integer, otherwise
+-1 will underflow to 65535.  When dragging a scrollbar, this would
+cause the scrollbar to snap to the bottom when the cursor is dragged
+above the window's y=0 coordinate.  Verified that the issue is fixed
+after this CL.
+
+BUG=1139623,1136352
+R=sky
+
+Change-Id: Ie318006ceadde9b9ce3e267fb453ddeba0e81da0
+Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2485620
+Auto-Submit: Thomas Anderson <thomasanderson@chromium.org>
+Commit-Queue: Scott Violet <sky@chromium.org>
+Reviewed-by: Scott Violet <sky@chromium.org>
+Cr-Commit-Position: refs/heads/master@{#819538}
+---
+ ui/events/x/events_x_utils.cc | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/ui/events/x/events_x_utils.cc b/ui/events/x/events_x_utils.cc
+index 3010db5f40c..856dfb221e7 100644
+--- a/ui/events/x/events_x_utils.cc
++++ b/ui/events/x/events_x_utils.cc
+@@ -376,7 +376,7 @@ base::TimeTicks TimeTicksFromXEvent(const x11::Event& xev) {
+ 
+ // This is ported from libxi's FP1616toDBL in XExtInt.c
+ double Fp1616ToDouble(x11::Input::Fp1616 x) {
+-  auto x32 = static_cast<uint32_t>(x);
++  auto x32 = static_cast<int32_t>(x);
+   return x32 * 1.0 / (1 << 16);
+ }
+