diff --git a/src/basic/process-util.c b/src/basic/process-util.c
index b1cdc4257d..99b0946a03 100644
--- a/src/basic/process-util.c
+++ b/src/basic/process-util.c
@@ -475,7 +475,7 @@ static int get_process_id(pid_t pid, const char *field, uid_t *uid) {
         assert(field);
         assert(uid);
 
-        if (!pid_is_valid(pid))
+        if (pid < 0)
                 return -EINVAL;
 
         p = procfs_file_alloca(pid, "status");
@@ -787,7 +787,7 @@ int getenv_for_pid(pid_t pid, const char *field, char **_value) {
 bool pid_is_unwaited(pid_t pid) {
         /* Checks whether a PID is still valid at all, including a zombie */
 
-        if (!pid_is_valid(pid))
+        if (pid < 0)
                 return false;
 
         if (pid <= 1) /* If we or PID 1 would be dead and have been waited for, this code would not be running */
@@ -807,7 +807,7 @@ bool pid_is_alive(pid_t pid) {
 
         /* Checks whether a PID is still valid and not a zombie */
 
-        if (!pid_is_valid(pid))
+        if (pid < 0)
                 return false;
 
         if (pid <= 1) /* If we or PID 1 would be a zombie, this code would not be running */
@@ -826,7 +826,7 @@ bool pid_is_alive(pid_t pid) {
 int pid_from_same_root_fs(pid_t pid) {
         const char *root;
 
-        if (!pid_is_valid(pid))
+        if (pid < 0)
                 return false;
 
         if (pid == 0 || pid == getpid_cached())
diff --git a/src/core/dbus-manager.c b/src/core/dbus-manager.c
index c91d56598b..f87b52a266 100644
--- a/src/core/dbus-manager.c
+++ b/src/core/dbus-manager.c
@@ -446,7 +446,7 @@ static int method_get_unit_by_pid(sd_bus_message *message, void *userdata, sd_bu
         r = sd_bus_message_read(message, "u", &pid);
         if (r < 0)
                 return r;
-        if (!pid_is_valid((pid_t) pid))
+        if (pid < 0)
                 return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid PID " PID_FMT, pid);
 
         if (pid == 0) {
diff --git a/src/login/logind-core.c b/src/login/logind-core.c
index 997c421e9a..ba538559f9 100644
--- a/src/login/logind-core.c
+++ b/src/login/logind-core.c
@@ -287,7 +287,7 @@ int manager_get_session_by_pid(Manager *m, pid_t pid, Session **session) {
 
         assert(m);
 
-        if (pid < 1)
+        if (!pid_is_valid(pid))
                 return -EINVAL;
 
         r = cg_pid_get_unit(pid, &unit);
@@ -311,7 +311,7 @@ int manager_get_user_by_pid(Manager *m, pid_t pid, User **user) {
         assert(m);
         assert(user);
 
-        if (pid < 1)
+        if (!pid_is_valid(pid))
                 return -EINVAL;
 
         r = cg_pid_get_slice(pid, &unit);
diff --git a/src/login/logind-dbus.c b/src/login/logind-dbus.c
index 1aa6760665..d66022f802 100644
--- a/src/login/logind-dbus.c
+++ b/src/login/logind-dbus.c
@@ -344,7 +344,7 @@ static int method_get_session_by_pid(sd_bus_message *message, void *userdata, sd
         r = sd_bus_message_read(message, "u", &pid);
         if (r < 0)
                 return r;
-        if (!pid_is_valid((pid_t) pid))
+        if (pid < 0)
                 return -EINVAL;
 
         if (pid == 0) {
@@ -407,7 +407,7 @@ static int method_get_user_by_pid(sd_bus_message *message, void *userdata, sd_bu
         r = sd_bus_message_read(message, "u", &pid);
         if (r < 0)
                 return r;
-        if (!pid_is_valid((pid_t) pid))
+        if (pid < 0)
                 return -EINVAL;
 
         if (pid == 0) {
diff --git a/src/machine/machined-dbus.c b/src/machine/machined-dbus.c
index 6618ec30f1..c9b92d2765 100644
--- a/src/machine/machined-dbus.c
+++ b/src/machine/machined-dbus.c
@@ -199,7 +199,7 @@ static int method_get_machine_by_pid(sd_bus_message *message, void *userdata, sd
         if (r < 0)
                 return r;
 
-        if (!pid_is_valid((pid_t) pid))
+        if (pid < 0)
                 return -EINVAL;
 
         if (pid == 0) {
diff --git a/src/systemctl/systemctl.c b/src/systemctl/systemctl.c
index 280d786daa..8d90850a53 100644
--- a/src/systemctl/systemctl.c
+++ b/src/systemctl/systemctl.c
@@ -3376,7 +3376,7 @@ static int logind_check_inhibitors(enum action a) {
                         return log_oom();
 
                 if (!pid_is_valid((pid_t) pid)) {
-                        log_error("Invalid PID %" PRIu32 ".", pid);
+                        log_error("Invalid PID "PID_FMT".", (pid_t) pid);
                         return -ERANGE;
                 }