diff --git a/src/basic/env-util.c b/src/basic/env-util.c
index 7bdfdec851..bbb6d5829b 100644
--- a/src/basic/env-util.c
+++ b/src/basic/env-util.c
@@ -688,7 +688,7 @@ static int strv_env_get_n_validated(
 
 int replace_env_full(
                 const char *format,
-                size_t n,
+                size_t length,
                 char **env,
                 ReplaceEnvFlags flags,
                 char **ret,
@@ -714,13 +714,13 @@ int replace_env_full(
 
         assert(format);
 
-        if (n == SIZE_MAX)
-                n = strlen(format);
+        if (length == SIZE_MAX)
+                length = strlen(format);
 
         pu = ret_unset_variables ? &unset_variables : NULL;
         pb = ret_bad_variables ? &bad_variables : NULL;
 
-        for (e = format, i = 0; *e && i < n; e++, i++)
+        for (e = format, i = 0; *e && i < length; e++, i++)
                 switch (state) {
 
                 case WORD:
diff --git a/src/basic/env-util.h b/src/basic/env-util.h
index 6c25ca3804..9f55a91fff 100644
--- a/src/basic/env-util.h
+++ b/src/basic/env-util.h
@@ -15,7 +15,7 @@ typedef enum ReplaceEnvFlags {
         REPLACE_ENV_ALLOW_EXTENDED  = 1 << 2,
 } ReplaceEnvFlags;
 
-int replace_env_full(const char *format, size_t n, char **env, ReplaceEnvFlags flags, char **ret, char ***ret_unset_variables, char ***ret_bad_variables);
+int replace_env_full(const char *format, size_t length, char **env, ReplaceEnvFlags flags, char **ret, char ***ret_unset_variables, char ***ret_bad_variables);
 static inline int replace_env(const char *format, char **env, ReplaceEnvFlags flags, char **ret) {
         return replace_env_full(format, SIZE_MAX, env, flags, ret, NULL, NULL);
 }
diff --git a/src/basic/io-util.c b/src/basic/io-util.c
index 69c275ae17..82fad1303f 100644
--- a/src/basic/io-util.c
+++ b/src/basic/io-util.c
@@ -188,10 +188,10 @@ int pipe_eof(int fd) {
         return !!(r & POLLHUP);
 }
 
-int ppoll_usec_full(struct pollfd *fds, size_t nfds, usec_t timeout, const sigset_t *ss) {
+int ppoll_usec_full(struct pollfd *fds, size_t n_fds, usec_t timeout, const sigset_t *ss) {
         int r;
 
-        assert(fds || nfds == 0);
+        assert(fds || n_fds == 0);
 
         /* This is a wrapper around ppoll() that does primarily two things:
          *
@@ -208,16 +208,16 @@ int ppoll_usec_full(struct pollfd *fds, size_t nfds, usec_t timeout, const sigse
          *  to handle signals, such as signalfd() or signal handlers. ⚠️ ⚠️ ⚠️
          */
 
-        if (nfds == 0 && timeout == 0)
+        if (n_fds == 0 && timeout == 0)
                 return 0;
 
-        r = ppoll(fds, nfds, timeout == USEC_INFINITY ? NULL : TIMESPEC_STORE(timeout), ss);
+        r = ppoll(fds, n_fds, timeout == USEC_INFINITY ? NULL : TIMESPEC_STORE(timeout), ss);
         if (r < 0)
                 return -errno;
         if (r == 0)
                 return 0;
 
-        for (size_t i = 0, n = r; i < nfds && n > 0; i++) {
+        for (size_t i = 0, n = r; i < n_fds && n > 0; i++) {
                 if (fds[i].revents == 0)
                         continue;
                 if (fds[i].revents & POLLNVAL)
diff --git a/src/basic/io-util.h b/src/basic/io-util.h
index f560b706b4..237a9ff77f 100644
--- a/src/basic/io-util.h
+++ b/src/basic/io-util.h
@@ -15,9 +15,9 @@ static inline int loop_write(int fd, const void *buf, size_t nbytes) {
 
 int pipe_eof(int fd);
 
-int ppoll_usec_full(struct pollfd *fds, size_t nfds, usec_t timeout, const sigset_t *ss) _nonnull_if_nonzero_(1, 2);
-_nonnull_if_nonzero_(1, 2) static inline int ppoll_usec(struct pollfd *fds, size_t nfds, usec_t timeout) {
-        return ppoll_usec_full(fds, nfds, timeout, NULL);
+int ppoll_usec_full(struct pollfd *fds, size_t n_fds, usec_t timeout, const sigset_t *ss) _nonnull_if_nonzero_(1, 2);
+_nonnull_if_nonzero_(1, 2) static inline int ppoll_usec(struct pollfd *fds, size_t n_fds, usec_t timeout) {
+        return ppoll_usec_full(fds, n_fds, timeout, NULL);
 }
 
 int fd_wait_for_event(int fd, int event, usec_t timeout);
diff --git a/src/basic/terminal-util.c b/src/basic/terminal-util.c
index b2a1c5c615..5f7b670389 100644
--- a/src/basic/terminal-util.c
+++ b/src/basic/terminal-util.c
@@ -735,7 +735,7 @@ int acquire_terminal(
                                                 .fd = notify,
                                                 .events = POLLIN,
                                         },
-                                        /* n_pollfds = */ 1,
+                                        /* n_fds = */ 1,
                                         left,
                                         &poll_ss);
                         if (r < 0)
diff --git a/src/basic/uid-range.c b/src/basic/uid-range.c
index 109bef51cb..2f20f0e1f1 100644
--- a/src/basic/uid-range.c
+++ b/src/basic/uid-range.c
@@ -367,7 +367,7 @@ int uid_map_search_root(pid_t pid, UIDRangeUsernsMode mode, uid_t *ret) {
         for (;;) {
                 uid_t uid_base = UID_INVALID, uid_shift = UID_INVALID;
 
-                r = uid_map_read_one(f, &uid_base, &uid_shift, /* ret_uid_range= */ NULL);
+                r = uid_map_read_one(f, &uid_base, &uid_shift, /* ret_range= */ NULL);
                 if (r < 0)
                         return r;
 
diff --git a/src/libsystemd/sd-journal/sd-journal.c b/src/libsystemd/sd-journal/sd-journal.c
index 8ec1fe450c..840f6d684b 100644
--- a/src/libsystemd/sd-journal/sd-journal.c
+++ b/src/libsystemd/sd-journal/sd-journal.c
@@ -2706,7 +2706,7 @@ _public_ int sd_journal_get_realtime_usec(sd_journal *j, uint64_t *ret) {
         return 0;
 }
 
-_public_ int sd_journal_get_monotonic_usec(sd_journal *j, uint64_t *ret, sd_id128_t *ret_boot_id) {
+_public_ int sd_journal_get_monotonic_usec(sd_journal *j, uint64_t *ret_monotonic, sd_id128_t *ret_boot_id) {
         JournalFile *f;
         Object *o;
         int r;
@@ -2739,8 +2739,8 @@ _public_ int sd_journal_get_monotonic_usec(sd_journal *j, uint64_t *ret, sd_id12
         if (!VALID_MONOTONIC(t))
                 return -EBADMSG;
 
-        if (ret)
-                *ret = t;
+        if (ret_monotonic)
+                *ret_monotonic = t;
         if (ret_boot_id)
                 *ret_boot_id = o->entry.boot_id;
 
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index c89f8723e6..f404e085a7 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -3757,7 +3757,7 @@ static int setup_unix_export_dir_outside(char **ret) {
          * itself is writable, but not through the mount accessible from the host. */
         r = mount_nofollow_verbose(
                         LOG_ERR,
-                        /* source= */ NULL,
+                        /* what= */ NULL,
                         w,
                         /* fstype= */ NULL,
                         MS_BIND|MS_REMOUNT|MS_RDONLY|MS_NODEV|MS_NOEXEC|MS_NOSUID|ms_nosymfollow_supported(),
@@ -3802,7 +3802,7 @@ static int setup_unix_export_host_inside(const char *directory, const char *unix
 
         r = mount_nofollow_verbose(
                         LOG_ERR,
-                        /* source= */ NULL,
+                        /* what= */ NULL,
                         p,
                         /* fstype= */ NULL,
                         MS_BIND|MS_REMOUNT|MS_NODEV|MS_NOEXEC|MS_NOSUID|ms_nosymfollow_supported(),
diff --git a/src/shared/install.h b/src/shared/install.h
index 0f9b0798aa..39bded38b8 100644
--- a/src/shared/install.h
+++ b/src/shared/install.h
@@ -112,7 +112,7 @@ int unit_file_reenable(
                 size_t *n_changes);
 int unit_file_preset(
                 RuntimeScope scope,
-                UnitFileFlags flags,
+                UnitFileFlags file_flags,
                 const char *root_dir,
                 char * const *names,
                 UnitFilePresetMode mode,
@@ -120,7 +120,7 @@ int unit_file_preset(
                 size_t *n_changes);
 int unit_file_preset_all(
                 RuntimeScope scope,
-                UnitFileFlags flags,
+                UnitFileFlags file_flags,
                 const char *root_dir,
                 UnitFilePresetMode mode,
                 InstallChange **changes,
diff --git a/src/shared/mount-util.c b/src/shared/mount-util.c
index 958b4d7e18..71ee5cf734 100644
--- a/src/shared/mount-util.c
+++ b/src/shared/mount-util.c
@@ -1983,7 +1983,7 @@ int path_is_network_fs_harder_at(int dir_fd, const char *path) {
                 return r;
 
         _cleanup_free_ char *fstype = NULL, *options = NULL;
-        r = path_get_mount_info_at(fd, /* path = */ NULL, &fstype, &options, /* source = */ NULL);
+        r = path_get_mount_info_at(fd, /* path = */ NULL, &fstype, &options, /* ret_source = */ NULL);
         if (r < 0)
                 return r;
 
diff --git a/src/systemd/sd-journal.h b/src/systemd/sd-journal.h
index ec1568904e..57dc8a8332 100644
--- a/src/systemd/sd-journal.h
+++ b/src/systemd/sd-journal.h
@@ -98,7 +98,7 @@ int sd_journal_previous_skip(sd_journal *j, uint64_t skip);
 int sd_journal_next_skip(sd_journal *j, uint64_t skip);
 
 int sd_journal_get_realtime_usec(sd_journal *j, uint64_t *ret);
-int sd_journal_get_monotonic_usec(sd_journal *j, uint64_t *ret, sd_id128_t *ret_boot_id);
+int sd_journal_get_monotonic_usec(sd_journal *j, uint64_t *ret_monotonic, sd_id128_t *ret_boot_id);
 int sd_journal_get_seqnum(sd_journal *j, uint64_t *ret_seqnum, sd_id128_t *ret_seqnum_id);
 
 int sd_journal_set_data_threshold(sd_journal *j, size_t sz);
diff --git a/src/systemd/sd-varlink.h b/src/systemd/sd-varlink.h
index d1f5087492..67d9cc3d94 100644
--- a/src/systemd/sd-varlink.h
+++ b/src/systemd/sd-varlink.h
@@ -239,7 +239,7 @@ int sd_varlink_server_listen_fd(sd_varlink_server *s, int fd);
 int sd_varlink_server_listen_auto(sd_varlink_server *s);
 int sd_varlink_server_listen_name(sd_varlink_server *s, const char *name);
 int sd_varlink_server_add_connection(sd_varlink_server *s, int fd, sd_varlink **ret);
-int sd_varlink_server_add_connection_pair(sd_varlink_server *s, int input_fd, int output_fd, const struct ucred *ucred_override, sd_varlink **ret);
+int sd_varlink_server_add_connection_pair(sd_varlink_server *s, int input_fd, int output_fd, const struct ucred *override_ucred, sd_varlink **ret);
 int sd_varlink_server_add_connection_stdio(sd_varlink_server *s, sd_varlink **ret);
 
 /* Bind callbacks */