diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index 8ecbd69031b..746c7cdfed0 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -2295,6 +2295,7 @@ static int unit_attach_pid_to_cgroup_via_bus(Unit *u, pid_t pid, const char *suf
 }
 
 int unit_attach_pids_to_cgroup(Unit *u, Set *pids, const char *suffix_path) {
+        _cleanup_free_ char *joined = NULL;
         CGroupMask delegated_mask;
         const char *p;
         void *pidp;
@@ -2320,8 +2321,13 @@ int unit_attach_pids_to_cgroup(Unit *u, Set *pids, const char *suffix_path) {
 
         if (isempty(suffix_path))
                 p = u->cgroup_path;
-        else
-                p = prefix_roota(u->cgroup_path, suffix_path);
+        else {
+                joined = path_join(u->cgroup_path, suffix_path);
+                if (!joined)
+                        return -ENOMEM;
+
+                p = joined;
+        }
 
         delegated_mask = unit_get_delegate_mask(u);
 
diff --git a/src/delta/delta.c b/src/delta/delta.c
index aa5a546bce5..a08d35e43c3 100644
--- a/src/delta/delta.c
+++ b/src/delta/delta.c
@@ -369,10 +369,12 @@ static int enumerate_dir(
 
 static int should_skip_path(const char *prefix, const char *suffix) {
 #if HAVE_SPLIT_USR
-        _cleanup_free_ char *target = NULL;
-        const char *dirname, *p;
+        _cleanup_free_ char *target = NULL, *dirname = NULL;
+        const char *p;
 
-        dirname = prefix_roota(prefix, suffix);
+        dirname = path_join(prefix, suffix);
+        if (!dirname)
+                return -ENOMEM;
 
         if (chase_symlinks(dirname, NULL, 0, &target, NULL) < 0)
                 return false;
diff --git a/src/gpt-auto-generator/gpt-auto-generator.c b/src/gpt-auto-generator/gpt-auto-generator.c
index fa56a8322d4..a95f384ecbc 100644
--- a/src/gpt-auto-generator/gpt-auto-generator.c
+++ b/src/gpt-auto-generator/gpt-auto-generator.c
@@ -415,9 +415,9 @@ static int add_automount(
                 const char *description,
                 usec_t timeout) {
 
-        _cleanup_free_ char *unit = NULL;
+        _cleanup_free_ char *unit = NULL, *p = NULL;
         _cleanup_fclose_ FILE *f = NULL;
-        const char *opt = "noauto", *p;
+        const char *opt = "noauto";
         int r;
 
         assert(id);
@@ -443,7 +443,10 @@ static int add_automount(
         if (r < 0)
                 return log_error_errno(r, "Failed to generate unit name: %m");
 
-        p = prefix_roota(arg_dest, unit);
+        p = path_join(arg_dest, unit);
+        if (!p)
+                return log_oom();
+
         f = fopen(p, "wxe");
         if (!f)
                 return log_error_errno(errno, "Failed to create unit file %s: %m", unit);
diff --git a/src/libsystemd/sd-device/sd-device.c b/src/libsystemd/sd-device/sd-device.c
index 8574337bda9..6bc4e6a019f 100644
--- a/src/libsystemd/sd-device/sd-device.c
+++ b/src/libsystemd/sd-device/sd-device.c
@@ -2128,8 +2128,8 @@ int device_get_cached_sysattr_value(sd_device *device, const char *key, const ch
 /* We cache all sysattr lookups. If an attribute does not exist, it is stored
  * with a NULL value in the cache, otherwise the returned string is stored */
 _public_ int sd_device_get_sysattr_value(sd_device *device, const char *sysattr, const char **ret_value) {
-        _cleanup_free_ char *value = NULL;
-        const char *path, *syspath;
+        _cleanup_free_ char *value = NULL, *path = NULL;
+        const char *syspath;
         struct stat statbuf;
         int r;
 
@@ -2145,7 +2145,10 @@ _public_ int sd_device_get_sysattr_value(sd_device *device, const char *sysattr,
         if (r < 0)
                 return r;
 
-        path = prefix_roota(syspath, sysattr);
+        path = path_join(syspath, sysattr);
+        if (!path)
+                return -ENOMEM;
+
         if (lstat(path, &statbuf) < 0) {
                 int k;
 
@@ -2227,8 +2230,8 @@ static void device_remove_cached_sysattr_value(sd_device *device, const char *_k
 }
 
 _public_ int sd_device_set_sysattr_value(sd_device *device, const char *sysattr, const char *_value) {
-        _cleanup_free_ char *value = NULL;
-        const char *syspath, *path;
+        _cleanup_free_ char *value = NULL, *path = NULL;
+        const char *syspath;
         size_t len;
         int r;
 
@@ -2247,7 +2250,9 @@ _public_ int sd_device_set_sysattr_value(sd_device *device, const char *sysattr,
         if (r < 0)
                 return r;
 
-        path = prefix_roota(syspath, sysattr);
+        path = path_join(syspath, sysattr);
+        if (!path)
+                return -ENOMEM;
 
         len = strlen(_value);
 
diff --git a/src/libsystemd/sd-journal/sd-journal.c b/src/libsystemd/sd-journal/sd-journal.c
index 3318f9217d9..2a46f11d8ad 100644
--- a/src/libsystemd/sd-journal/sd-journal.c
+++ b/src/libsystemd/sd-journal/sd-journal.c
@@ -1375,7 +1375,7 @@ static int add_file_by_name(
                 const char *prefix,
                 const char *filename) {
 
-        const char *path;
+        _cleanup_free_ char *path = NULL;
 
         assert(j);
         assert(prefix);
@@ -1387,28 +1387,35 @@ static int add_file_by_name(
         if (!file_type_wanted(j->flags, filename))
                 return 0;
 
-        path = prefix_roota(prefix, filename);
+        path = path_join(prefix, filename);
+        if (!path)
+                return -ENOMEM;
+
         return add_any_file(j, -1, path);
 }
 
-static void remove_file_by_name(
+static int remove_file_by_name(
                 sd_journal *j,
                 const char *prefix,
                 const char *filename) {
 
-        const char *path;
+        _cleanup_free_ char *path = NULL;
         JournalFile *f;
 
         assert(j);
         assert(prefix);
         assert(filename);
 
-        path = prefix_roota(prefix, filename);
+        path = path_join(prefix, filename);
+        if (!path)
+                return -ENOMEM;
+
         f = ordered_hashmap_get(j->files, path);
         if (!f)
-                return;
+                return 0;
 
         remove_file_real(j, f);
+        return 1;
 }
 
 static void remove_file_real(sd_journal *j, JournalFile *f) {
@@ -2620,7 +2627,7 @@ static void process_inotify_event(sd_journal *j, const struct inotify_event *e)
                         if (e->mask & (IN_CREATE|IN_MOVED_TO|IN_MODIFY|IN_ATTRIB))
                                 (void) add_file_by_name(j, d->path, e->name);
                         else if (e->mask & (IN_DELETE|IN_MOVED_FROM|IN_UNMOUNT))
-                                remove_file_by_name(j, d->path, e->name);
+                                (void) remove_file_by_name(j, d->path, e->name);
 
                 } else if (!d->is_root && e->len == 0) {
 
diff --git a/src/portable/portable.c b/src/portable/portable.c
index c6e74e9c27d..256362355c0 100644
--- a/src/portable/portable.c
+++ b/src/portable/portable.c
@@ -873,6 +873,8 @@ static int portable_changes_add_with_prefix(
                 const char *path,
                 const char *source) {
 
+        _cleanup_free_ char *path_buf = NULL, *source_buf = NULL;
+
         assert(path);
         assert(!changes == !n_changes);
 
@@ -880,10 +882,19 @@ static int portable_changes_add_with_prefix(
                 return 0;
 
         if (prefix) {
-                path = prefix_roota(prefix, path);
+                path_buf = path_join(prefix, path);
+                if (!path_buf)
+                        return -ENOMEM;
 
-                if (source)
-                        source = prefix_roota(prefix, source);
+                path = path_buf;
+
+                if (source) {
+                        source_buf = path_join(prefix, source);
+                        if (!source_buf)
+                                return -ENOMEM;
+
+                        source = source_buf;
+                }
         }
 
         return portable_changes_add(changes, n_changes, type_or_errno, path, source);
@@ -1098,7 +1109,8 @@ static int attach_unit_file(
 
         _cleanup_(unlink_and_freep) char *chroot_dropin = NULL, *profile_dropin = NULL;
         _cleanup_(rmdir_and_freep) char *dropin_dir = NULL;
-        const char *where, *path;
+        _cleanup_free_ char *path = NULL;
+        const char *where;
         int r;
 
         assert(paths);
@@ -1115,7 +1127,10 @@ static int attach_unit_file(
         } else
                 (void) portable_changes_add(changes, n_changes, PORTABLE_MKDIR, where, NULL);
 
-        path = prefix_roota(where, m->name);
+        path = path_join(where, m->name);
+        if (!path)
+                return -ENOMEM;
+
         dropin_dir = strjoin(path, ".d");
         if (!dropin_dir)
                 return -ENOMEM;
diff --git a/src/shared/generator.c b/src/shared/generator.c
index b4efcf6d0bd..681b97c6bd5 100644
--- a/src/shared/generator.c
+++ b/src/shared/generator.c
@@ -29,11 +29,13 @@ int generator_open_unit_file(
                 const char *name,
                 FILE **file) {
 
-        const char *unit;
+        _cleanup_free_ char *unit = NULL;
         FILE *f;
         int r;
 
-        unit = prefix_roota(dest, name);
+        unit = path_join(dest, name);
+        if (!unit)
+                return log_oom();
 
         r = fopen_unlocked(unit, "wxe", &f);
         if (r < 0) {
@@ -352,8 +354,8 @@ int generator_hook_up_mkswap(
                 const char *what) {
 
         _cleanup_free_ char *node = NULL, *unit = NULL, *escaped = NULL, *where_unit = NULL;
+        _cleanup_free_ char *unit_file = NULL;
         _cleanup_fclose_ FILE *f = NULL;
-        const char *unit_file;
         int r;
 
         node = fstab_node_to_udev_node(what);
@@ -371,7 +373,10 @@ int generator_hook_up_mkswap(
                 return log_error_errno(r, "Failed to make unit instance name from path \"%s\": %m",
                                        node);
 
-        unit_file = prefix_roota(dir, unit);
+        unit_file = path_join(dir, unit);
+        if (!unit_file)
+                return log_oom();
+
         log_debug("Creating %s", unit_file);
 
         escaped = cescape(node);
@@ -421,9 +426,8 @@ int generator_hook_up_mkfs(
                 const char *where,
                 const char *type) {
 
-        _cleanup_free_ char *node = NULL, *unit = NULL, *escaped = NULL, *where_unit = NULL;
+        _cleanup_free_ char *node = NULL, *unit = NULL, *unit_file = NULL, *escaped = NULL, *where_unit = NULL;
         _cleanup_fclose_ FILE *f = NULL;
-        const char *unit_file;
         int r;
 
         node = fstab_node_to_udev_node(what);
@@ -446,7 +450,10 @@ int generator_hook_up_mkfs(
                 return log_error_errno(r, "Failed to make unit instance name from path \"%s\": %m",
                                        node);
 
-        unit_file = prefix_roota(dir, unit);
+        unit_file = path_join(dir, unit);
+        if (!unit_file)
+                return log_oom();
+
         log_debug("Creating %s", unit_file);
 
         escaped = cescape(node);
@@ -499,9 +506,8 @@ int generator_hook_up_growfs(
                 const char *where,
                 const char *target) {
 
-        _cleanup_free_ char *unit = NULL, *escaped = NULL, *where_unit = NULL;
+        _cleanup_free_ char *unit = NULL, *escaped = NULL, *where_unit = NULL, *unit_file = NULL;
         _cleanup_fclose_ FILE *f = NULL;
-        const char *unit_file;
         int r;
 
         assert(dir);
@@ -521,7 +527,10 @@ int generator_hook_up_growfs(
                 return log_error_errno(r, "Failed to make unit name from path \"%s\": %m",
                                        where);
 
-        unit_file = prefix_roota(dir, unit);
+        unit_file = path_join(dir, unit);
+        if (!unit_file)
+                return log_oom();
+
         log_debug("Creating %s", unit_file);
 
         f = fopen(unit_file, "wxe");
diff --git a/src/sysv-generator/sysv-generator.c b/src/sysv-generator/sysv-generator.c
index 14ae873dc05..3c5df6c3ec8 100644
--- a/src/sysv-generator/sysv-generator.c
+++ b/src/sysv-generator/sysv-generator.c
@@ -80,16 +80,16 @@ static void free_sysvstub_hashmapp(Hashmap **h) {
 }
 
 static int add_alias(const char *service, const char *alias) {
-        const char *link;
-        int r;
+        _cleanup_free_ char *link = NULL;
 
         assert(service);
         assert(alias);
 
-        link = prefix_roota(arg_dest, alias);
+        link = path_join(arg_dest, alias);
+        if (!link)
+                return -ENOMEM;
 
-        r = symlink(service, link);
-        if (r < 0) {
+        if (symlink(service, link) < 0) {
                 if (errno == EEXIST)
                         return 0;
 
@@ -100,9 +100,8 @@ static int add_alias(const char *service, const char *alias) {
 }
 
 static int generate_unit_file(SysvStub *s) {
-        _cleanup_free_ char *path_escaped = NULL;
+        _cleanup_free_ char *path_escaped = NULL, *unit = NULL;
         _cleanup_fclose_ FILE *f = NULL;
-        const char *unit;
         int r;
 
         assert(s);
@@ -114,7 +113,9 @@ static int generate_unit_file(SysvStub *s) {
         if (!path_escaped)
                 return log_oom();
 
-        unit = prefix_roota(arg_dest, s->name);
+        unit = path_join(arg_dest, s->name);
+        if (!unit)
+                return log_oom();
 
         /* We might already have a symlink with the same name from a Provides:,
          * or from backup files like /etc/init.d/foo.bak. Real scripts always win,