diff --git a/lib/posix/posix.nim b/lib/posix/posix.nim
index fbe945df33..8c82122982 100644
--- a/lib/posix/posix.nim
+++ b/lib/posix/posix.nim
@@ -1095,7 +1095,21 @@ proc setprotoent*(a1: cint) {.importc, header: "<netdb.h>".}
 proc setservent*(a1: cint) {.importc, header: "<netdb.h>".}
 
 when not defined(lwip):
-  proc poll*(a1: ptr TPollfd, a2: Tnfds, a3: int): cint {.
+  # Linux and Haiku emulate SVR4, which used unsigned long.
+  # Meanwhile, BSD derivatives had used unsigned int; we will use this
+  # for the else case, because it is more widely cloned than SVR4's
+  # behavior.
+  when defined(linux) or defined(haiku):
+    type
+      Tnfds* {.importc: "nfds_t", header: "<poll.h>".} = culong
+  elif defined(zephyr):
+    type
+      Tnfds* = distinct cint
+  else:
+    type
+      Tnfds* {.importc: "nfds_t", header: "<poll.h>".} = cuint
+
+  proc poll*(a1: ptr TPollfd, a2: Tnfds, a3: cint): cint {.
     importc, header: "<poll.h>", sideEffect.}
 
 proc realpath*(name, resolved: cstring): cstring {.
diff --git a/lib/posix/posix_haiku.nim b/lib/posix/posix_haiku.nim
index 32a6d24e26..abfb2b9bda 100644
--- a/lib/posix/posix_haiku.nim
+++ b/lib/posix/posix_haiku.nim
@@ -519,8 +519,6 @@ type
     events*: cshort  ## The input event flags (see below).
     revents*: cshort ## The output event flags (see below).
 
-  Tnfds* {.importc: "nfds_t", header: "<poll.h>".} = culong
-
 var
   errno* {.importc, header: "<errno.h>".}: cint ## error variable
   h_errno* {.importc, header: "<netdb.h>".}: cint
diff --git a/lib/posix/posix_linux_amd64.nim b/lib/posix/posix_linux_amd64.nim
index 8d11c507d7..7a9126abed 100644
--- a/lib/posix/posix_linux_amd64.nim
+++ b/lib/posix/posix_linux_amd64.nim
@@ -563,8 +563,6 @@ type
     events*: cshort  ## The input event flags (see below).
     revents*: cshort ## The output event flags (see below).
 
-  Tnfds* {.importc: "nfds_t", header: "<poll.h>".} = culong
-
 var
   errno* {.importc, header: "<errno.h>".}: cint ## error variable
   h_errno* {.importc, header: "<netdb.h>".}: cint
diff --git a/lib/posix/posix_macos_amd64.nim b/lib/posix/posix_macos_amd64.nim
index 366181846d..8581411096 100644
--- a/lib/posix/posix_macos_amd64.nim
+++ b/lib/posix/posix_macos_amd64.nim
@@ -529,8 +529,6 @@ type
     events*: cshort  ## The input event flags (see below).
     revents*: cshort ## The output event flags (see below).
 
-  Tnfds* {.importc: "nfds_t", header: "<poll.h>".} = cint
-
 var
   errno* {.importc, header: "<errno.h>".}: cint ## error variable
   h_errno* {.importc, header: "<netdb.h>".}: cint
diff --git a/lib/posix/posix_nintendoswitch.nim b/lib/posix/posix_nintendoswitch.nim
index b66563695c..fdc4e590e4 100644
--- a/lib/posix/posix_nintendoswitch.nim
+++ b/lib/posix/posix_nintendoswitch.nim
@@ -484,8 +484,6 @@ type
     events*: cshort  ## The input event flags (see below).
     revents*: cshort ## The output event flags (see below).
 
-  Tnfds* {.importc: "nfds_t", header: "<poll.h>".} = culong
-
 var
   errno* {.importc, header: "<errno.h>".}: cint ## error variable
   h_errno* {.importc, header: "<netdb.h>".}: cint
diff --git a/lib/posix/posix_openbsd_amd64.nim b/lib/posix/posix_openbsd_amd64.nim
index fbe72511cf..9f6612d04c 100644
--- a/lib/posix/posix_openbsd_amd64.nim
+++ b/lib/posix/posix_openbsd_amd64.nim
@@ -513,8 +513,6 @@ type
     events*: cshort  ## The input event flags (see below).
     revents*: cshort ## The output event flags (see below).
 
-  Tnfds* {.importc: "nfds_t", header: "<poll.h>".} = cint
-
 var
   errno* {.importc, header: "<errno.h>".}: cint ## error variable
   h_errno* {.importc, header: "<netdb.h>".}: cint
diff --git a/lib/posix/posix_other.nim b/lib/posix/posix_other.nim
index 7301b64d6a..c74b2e4c01 100644
--- a/lib/posix/posix_other.nim
+++ b/lib/posix/posix_other.nim
@@ -604,13 +604,6 @@ when not defined(lwip):
       events*: cshort  ## The input event flags (see below).
       revents*: cshort ## The output event flags (see below).
 
-  when defined(zephyr):
-    type
-      Tnfds* = distinct culong
-  else:
-    type
-      Tnfds* {.importc: "nfds_t", header: "<poll.h>".} = culong
-
 var
   errno* {.importc, header: "<errno.h>".}: cint ## error variable
   h_errno* {.importc, header: "<netdb.h>".}: cint
diff --git a/lib/pure/ioselects/ioselectors_poll.nim b/lib/pure/ioselects/ioselectors_poll.nim
index 12812ac807..64b1937113 100644
--- a/lib/pure/ioselects/ioselectors_poll.nim
+++ b/lib/pure/ioselects/ioselectors_poll.nim
@@ -231,7 +231,7 @@ proc selectInto*[T](s: Selector[T], timeout: int,
   verifySelectParams(timeout)
 
   s.withPollLock():
-    let count = posix.poll(addr(s.pollfds[0]), Tnfds(s.pollcnt), timeout)
+    let count = posix.poll(addr(s.pollfds[0]), Tnfds(s.pollcnt), cint(timeout))
     if count < 0:
       result = 0
       let err = osLastError()
diff --git a/lib/pure/net.nim b/lib/pure/net.nim
index deb9cb0673..fdd2fdc5f2 100644
--- a/lib/pure/net.nim
+++ b/lib/pure/net.nim
@@ -211,7 +211,7 @@ when defined(nimHasStyleChecks):
 when defined(posix) and not defined(lwip):
   from posix import TPollfd, POLLIN, POLLPRI, POLLOUT, POLLWRBAND, Tnfds
 
-  template monitorPollEvent(x: var SocketHandle, y: cint, timeout: int): int =
+  template monitorPollEvent(x: var SocketHandle, y, timeout: cint): int =
     var tpollfd: TPollfd
     tpollfd.fd = cast[cint](x)
     tpollfd.events = y
@@ -222,14 +222,14 @@ proc timeoutRead(fd: var SocketHandle, timeout = 500): int =
     var fds = @[fd]
     selectRead(fds, timeout)
   else:
-    monitorPollEvent(fd, POLLIN or POLLPRI, timeout)
+    monitorPollEvent(fd, POLLIN or POLLPRI, cint(timeout))
 
 proc timeoutWrite(fd: var SocketHandle, timeout = 500): int =
   when defined(windows) or defined(lwip):
     var fds = @[fd]
     selectWrite(fds, timeout)
   else:
-    monitorPollEvent(fd, POLLOUT or POLLWRBAND, timeout)
+    monitorPollEvent(fd, POLLOUT or POLLWRBAND, cint(timeout))
 
 proc socketError*(socket: Socket, err: int = -1, async = false,
                   lastError = (-1).OSErrorCode,