diff --git a/src/unix/lwt_unix.h b/src/unix/lwt_unix.h
index 47f093016..ab4ad64bf 100644
--- a/src/unix/lwt_unix.h
+++ b/src/unix/lwt_unix.h
@@ -14,9 +14,14 @@
 #include <caml/socketaddr.h>
 #include <string.h>
 
+// The following macro is for backwards compatibility.
+// It is given an `lwt_` prefix to avoid name collisions for code which
+// include both this file and alloc.h.
 #if OCAML_VERSION < 50000
-#define caml_convert_flag_list(flags, table) \
+#define lwt_convert_flag_list(flags, table) \
     caml_convert_flag_list((flags), (int *)(table))
+#else
+#define lwt_convert_flag_list caml_convert_flag_list
 #endif
 
 /* The macro to get the file-descriptor from a value. */
diff --git a/src/unix/unix_c/unix_bytes_recv.c b/src/unix/unix_c/unix_bytes_recv.c
index fac0ebda8..a535bc07c 100644
--- a/src/unix/unix_c/unix_bytes_recv.c
+++ b/src/unix/unix_c/unix_bytes_recv.c
@@ -23,7 +23,7 @@ value lwt_unix_bytes_recv(value fd, value buf, value ofs, value len,
     int ret;
     ret =
         recv(Int_val(fd), (char *)Caml_ba_array_val(buf)->data + Long_val(ofs),
-             Long_val(len), caml_convert_flag_list(flags, msg_flag_table));
+             Long_val(len), lwt_convert_flag_list(flags, msg_flag_table));
     if (ret == -1) uerror("recv", Nothing);
     return Val_int(ret);
 }
diff --git a/src/unix/unix_c/unix_bytes_recvfrom.c b/src/unix/unix_c/unix_bytes_recvfrom.c
index 1ae1c65a1..b05b221e6 100644
--- a/src/unix/unix_c/unix_bytes_recvfrom.c
+++ b/src/unix/unix_c/unix_bytes_recvfrom.c
@@ -29,7 +29,7 @@ value lwt_unix_bytes_recvfrom(value fd, value buf, value ofs, value len,
     socklen_t addr_len;
     addr_len = sizeof(addr);
     ret = recvfrom(Int_val(fd), (char *)Caml_ba_data_val(buf) + Long_val(ofs),
-                   Long_val(len), caml_convert_flag_list(flags, msg_flag_table),
+                   Long_val(len), lwt_convert_flag_list(flags, msg_flag_table),
                    &addr.s_gen, &addr_len);
     if (ret == -1) uerror("recvfrom", Nothing);
     address = alloc_sockaddr(&addr, addr_len, -1);
diff --git a/src/unix/unix_c/unix_bytes_send.c b/src/unix/unix_c/unix_bytes_send.c
index 2bdd44a34..558afdd38 100644
--- a/src/unix/unix_c/unix_bytes_send.c
+++ b/src/unix/unix_c/unix_bytes_send.c
@@ -23,7 +23,7 @@ value lwt_unix_bytes_send(value fd, value buf, value ofs, value len,
     int ret;
     ret =
         send(Int_val(fd), (char *)Caml_ba_array_val(buf)->data + Long_val(ofs),
-             Long_val(len), caml_convert_flag_list(flags, msg_flag_table));
+             Long_val(len), lwt_convert_flag_list(flags, msg_flag_table));
     if (ret == -1) uerror("send", Nothing);
     return Val_int(ret);
 }
diff --git a/src/unix/unix_c/unix_bytes_sendto.c b/src/unix/unix_c/unix_bytes_sendto.c
index e9610b895..a555b534f 100644
--- a/src/unix/unix_c/unix_bytes_sendto.c
+++ b/src/unix/unix_c/unix_bytes_sendto.c
@@ -26,7 +26,7 @@ value lwt_unix_bytes_sendto(value fd, value buf, value ofs, value len,
     int ret;
     get_sockaddr(dest, &addr, &addr_len);
     ret = sendto(Int_val(fd), (char *)Caml_ba_data_val(buf) + Long_val(ofs),
-                 Long_val(len), caml_convert_flag_list(flags, msg_flag_table),
+                 Long_val(len), lwt_convert_flag_list(flags, msg_flag_table),
                  &addr.s_gen, addr_len);
     if (ret == -1) uerror("send", Nothing);
     return Val_int(ret);
diff --git a/src/unix/unix_c/unix_getnameinfo_job.c b/src/unix/unix_c/unix_getnameinfo_job.c
index 8f5e3bbdb..608dcd3bb 100644
--- a/src/unix/unix_c/unix_getnameinfo_job.c
+++ b/src/unix/unix_c/unix_getnameinfo_job.c
@@ -60,7 +60,7 @@ CAMLprim value lwt_unix_getnameinfo_job(value sockaddr, value opts)
 {
     LWT_UNIX_INIT_JOB(job, getnameinfo, 0);
     get_sockaddr(sockaddr, &job->addr, &job->addr_len);
-    job->opts = caml_convert_flag_list(opts, getnameinfo_flag_table);
+    job->opts = lwt_convert_flag_list(opts, getnameinfo_flag_table);
     return lwt_unix_alloc_job(&job->job);
 }
 #endif
diff --git a/src/unix/unix_c/unix_open_job.c b/src/unix/unix_c/unix_open_job.c
index 0c1be8459..675fc3db6 100644
--- a/src/unix/unix_c/unix_open_job.c
+++ b/src/unix/unix_c/unix_open_job.c
@@ -113,8 +113,8 @@ static value result_open(struct job_open *job)
 CAMLprim value lwt_unix_open_job(value name, value flags, value perms)
 {
     LWT_UNIX_INIT_JOB_STRING(job, open, 0, name);
-    job->fd = caml_convert_flag_list(flags, open_cloexec_table);
-    job->flags = caml_convert_flag_list(flags, open_flag_table);
+    job->fd = lwt_convert_flag_list(flags, open_cloexec_table);
+    job->flags = lwt_convert_flag_list(flags, open_flag_table);
     job->perms = Int_val(perms);
     return lwt_unix_alloc_job(&(job->job));
 }
diff --git a/src/unix/unix_c/unix_recv.c b/src/unix/unix_c/unix_recv.c
index 4456d7421..d3fec45fb 100644
--- a/src/unix/unix_c/unix_recv.c
+++ b/src/unix/unix_c/unix_recv.c
@@ -20,7 +20,7 @@ value lwt_unix_recv(value fd, value buf, value ofs, value len, value flags)
 {
     int ret;
     ret = recv(Int_val(fd), &Byte(String_val(buf), Long_val(ofs)),
-               Long_val(len), caml_convert_flag_list(flags, msg_flag_table));
+               Long_val(len), lwt_convert_flag_list(flags, msg_flag_table));
     if (ret == -1) uerror("recv", Nothing);
     return Val_int(ret);
 }
diff --git a/src/unix/unix_c/unix_recvfrom.c b/src/unix/unix_c/unix_recvfrom.c
index fd86c247a..2b50a7203 100644
--- a/src/unix/unix_c/unix_recvfrom.c
+++ b/src/unix/unix_c/unix_recvfrom.c
@@ -27,7 +27,7 @@ value lwt_unix_recvfrom(value fd, value buf, value ofs, value len, value flags)
     socklen_t addr_len;
     addr_len = sizeof(addr);
     ret = recvfrom(Int_val(fd), &Byte(String_val(buf), Long_val(ofs)),
-                   Long_val(len), caml_convert_flag_list(flags, msg_flag_table),
+                   Long_val(len), lwt_convert_flag_list(flags, msg_flag_table),
                    &addr.s_gen, &addr_len);
     if (ret == -1) uerror("recvfrom", Nothing);
     address = alloc_sockaddr(&addr, addr_len, -1);
diff --git a/src/unix/unix_c/unix_send.c b/src/unix/unix_c/unix_send.c
index fc4ba34be..efecc8f41 100644
--- a/src/unix/unix_c/unix_send.c
+++ b/src/unix/unix_c/unix_send.c
@@ -20,7 +20,7 @@ value lwt_unix_send(value fd, value buf, value ofs, value len, value flags)
 {
     int ret;
     ret = send(Int_val(fd), &Byte(String_val(buf), Long_val(ofs)),
-               Long_val(len), caml_convert_flag_list(flags, msg_flag_table));
+               Long_val(len), lwt_convert_flag_list(flags, msg_flag_table));
     if (ret == -1) uerror("send", Nothing);
     return Val_int(ret);
 }
diff --git a/src/unix/unix_c/unix_sendto.c b/src/unix/unix_c/unix_sendto.c
index 8a993e669..845f7edd0 100644
--- a/src/unix/unix_c/unix_sendto.c
+++ b/src/unix/unix_c/unix_sendto.c
@@ -25,7 +25,7 @@ value lwt_unix_sendto(value fd, value buf, value ofs, value len, value flags,
     int ret;
     get_sockaddr(dest, &addr, &addr_len);
     ret = sendto(Int_val(fd), &Byte(String_val(buf), Long_val(ofs)),
-                 Long_val(len), caml_convert_flag_list(flags, msg_flag_table),
+                 Long_val(len), lwt_convert_flag_list(flags, msg_flag_table),
                  &addr.s_gen, addr_len);
     if (ret == -1) uerror("send", Nothing);
     return Val_int(ret);
diff --git a/src/unix/unix_c/unix_wait4.c b/src/unix/unix_c/unix_wait4.c
index ee0acf5e8..86925c424 100644
--- a/src/unix/unix_c/unix_wait4.c
+++ b/src/unix/unix_c/unix_wait4.c
@@ -67,7 +67,7 @@ value lwt_unix_wait4(value flags, value pid_req)
     CAMLlocal2(times, res);
 
     int pid, status, cv_flags;
-    cv_flags = caml_convert_flag_list(flags, wait_flag_table);
+    cv_flags = lwt_convert_flag_list(flags, wait_flag_table);
 
     struct rusage ru;