diff --git a/src/core/ngx_cycle.c b/src/core/ngx_cycle.c
index 87cb62e..98599f3 100644
--- a/src/core/ngx_cycle.c
+++ b/src/core/ngx_cycle.c
@@ -1006,7 +1006,7 @@
 ngx_signal_process(ngx_cycle_t *cycle, char *sig)
 {
     ssize_t           n;
-    ngx_int_t         pid;
+    ngx_pid_t         pid;
     ngx_file_t        file;
     ngx_core_conf_t  *ccf;
     u_char            buf[NGX_INT64_LEN + 2];
@@ -1044,7 +1044,7 @@
 
     pid = ngx_atoi(buf, ++n);
 
-    if (pid == NGX_ERROR) {
+    if (pid == (ngx_pid_t) NGX_ERROR) {
         ngx_log_error(NGX_LOG_ERR, cycle->log, 0,
                       "invalid PID number \"%*s\" in \"%s\"",
                       n, buf, file.name.data);
diff --git a/src/os/unix/ngx_os.h b/src/os/unix/ngx_os.h
index c0d59ef..e22f07c 100644
--- a/src/os/unix/ngx_os.h
+++ b/src/os/unix/ngx_os.h
@@ -39,7 +39,7 @@
 ngx_int_t ngx_os_specific_init(ngx_log_t *log);
 void ngx_os_specific_status(ngx_log_t *log);
 ngx_int_t ngx_daemon(ngx_log_t *log);
-ngx_int_t ngx_os_signal_process(ngx_cycle_t *cycle, char *sig, ngx_int_t pid);
+ngx_int_t ngx_os_signal_process(ngx_cycle_t *cycle, char *sig, ngx_pid_t pid);
 
 
 ssize_t ngx_unix_recv(ngx_connection_t *c, u_char *buf, size_t size);
diff --git a/src/os/unix/ngx_process.c b/src/os/unix/ngx_process.c
index ffc2a2a..24a63fb 100644
--- a/src/os/unix/ngx_process.c
+++ b/src/os/unix/ngx_process.c
@@ -611,7 +611,7 @@
 
 
 ngx_int_t
-ngx_os_signal_process(ngx_cycle_t *cycle, char *name, ngx_int_t pid)
+ngx_os_signal_process(ngx_cycle_t *cycle, char *name, ngx_pid_t pid)
 {
     ngx_signal_t  *sig;
 
@@ -622,7 +622,7 @@
             }
 
             ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
-                          "kill(%P, %d) failed", (ngx_pid_t) pid, sig->signo);
+                          "kill(%P, %d) failed", pid, sig->signo);
         }
     }
 
diff --git a/src/os/win32/ngx_os.h b/src/os/win32/ngx_os.h
index 8bce9a2..98210a1 100644
--- a/src/os/win32/ngx_os.h
+++ b/src/os/win32/ngx_os.h
@@ -35,7 +35,7 @@
 
 ngx_int_t ngx_os_init(ngx_log_t *log);
 void ngx_os_status(ngx_log_t *log);
-ngx_int_t ngx_os_signal_process(ngx_cycle_t *cycle, char *sig, ngx_int_t pid);
+ngx_int_t ngx_os_signal_process(ngx_cycle_t *cycle, char *sig, ngx_pid_t pid);
 
 ssize_t ngx_wsarecv(ngx_connection_t *c, u_char *buf, size_t size);
 ssize_t ngx_overlapped_wsarecv(ngx_connection_t *c, u_char *buf, size_t size);
diff --git a/src/os/win32/ngx_process_cycle.c b/src/os/win32/ngx_process_cycle.c
index 699a559..3ebadbe 100644
--- a/src/os/win32/ngx_process_cycle.c
+++ b/src/os/win32/ngx_process_cycle.c
@@ -1001,13 +1001,13 @@
 
 
 ngx_int_t
-ngx_os_signal_process(ngx_cycle_t *cycle, char *sig, ngx_int_t pid)
+ngx_os_signal_process(ngx_cycle_t *cycle, char *sig, ngx_pid_t pid)
 {
     HANDLE     ev;
     ngx_int_t  rc;
     char       evn[NGX_PROCESS_SYNC_NAME];
 
-    ngx_sprintf((u_char *) evn, "Global\\ngx_%s_%P%Z", sig, (ngx_pid_t) pid);
+    ngx_sprintf((u_char *) evn, "Global\\ngx_%s_%P%Z", sig, pid);
 
     ev = OpenEvent(EVENT_MODIFY_STATE, 0, evn);
     if (ev == NULL) {