diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b5be5e5..4e235e3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,11 +11,11 @@ jobs:
         arch: [i386, amd64]
         include:
           - target: linux
-            builder: ubuntu-20.04
+            builder: ubuntu-22.04
           - target: macos
-            builder: macos-11
+            builder: macos-12
           - target: windows
-            builder: windows-2019
+            builder: windows-2022
           - target: linux
             arch: amd64
             branch: devel
@@ -23,7 +23,8 @@ jobs:
         exclude:
           - target: macos
             arch: i386
-    name: "${{ matrix.target }} on ${{ matrix.arch }} (Nim ${{ matrix.branch }})"
+    name:
+      "${{ matrix.target }} on ${{ matrix.arch }} (Nim ${{ matrix.branch }})"
     runs-on: ${{ matrix.builder }}
 
     defaults:
@@ -60,6 +61,12 @@ jobs:
           platform: x86
           static: 0
 
+      - name: Install valgrind (Linux-only)
+        if: runner.os == 'Linux'
+        run: |
+          sudo apt-fast update -qq
+          sudo DEBIAN_FRONTEND='noninteractive' apt-fast install -yq valgrind
+
       - name: Setup Nim
         uses: alaviss/setup-nim@0.1.1
         with:
@@ -90,8 +97,8 @@ jobs:
 
       - name: Publish docs
         if: >
-          matrix.pushdocs && github.event_name == 'push' &&
-          github.ref == 'refs/heads/master'
+          matrix.pushdocs && github.event_name == 'push' && github.ref ==
+          'refs/heads/master'
         uses: crazy-max/ghaction-github-pages@v3.0.0
         with:
           build_dir: nim-sys/htmldocs
diff --git a/src/sys/private/syscall/linux/epoll.nim b/src/sys/private/syscall/linux/epoll.nim
index ad5815a..508bcb8 100644
--- a/src/sys/private/syscall/linux/epoll.nim
+++ b/src/sys/private/syscall/linux/epoll.nim
@@ -87,7 +87,8 @@ proc create*(flags: cint): FD {.cdecl, importc: "epoll_create1".}
 proc ctl*(epfd: FD, op: CtlOp, fd: handles.FD, event: ptr Event): cint
          {.cdecl, importc: "epoll_ctl".}
 proc ctl*(epfd: FD, op: CtlOp, fd: handles.FD, event: var Event): cint
-         {.cdecl, importc: "epoll_ctl".}
+         {.inline.} =
+  ctl(epfd, op, fd, addr event)
 
 proc wait*(epfd: FD, events: ptr UncheckedArray[Event], maxevents: cint,
            timeout: cint): cint {.cdecl, importc: "epoll_wait".}
diff --git a/sys.nimble b/sys.nimble
index 363fb7d..4fc72ed 100644
--- a/sys.nimble
+++ b/sys.nimble
@@ -10,7 +10,7 @@ srcDir        = "src"
 # Dependencies
 
 requires "nim >= 1.5.1"
-requires "https://github.com/disruptek/balls >= 3.9.0 & < 4.0.0"
+requires "https://github.com/disruptek/balls >= 5.0.0 & < 6.0.0"
 when (NimMajor, NimMinor, NimPatch) < (1, 9, 0):
   requires "https://github.com/nim-works/cps >= 0.8.0 & < 0.9.0"
 else: