diff --git a/src/basic/fileio.c b/src/basic/fileio.c
index 1ce7b85fba1..3ab50bca2f7 100644
--- a/src/basic/fileio.c
+++ b/src/basic/fileio.c
@@ -167,6 +167,9 @@ int write_string_file_ts(
                 }
         }
 
+        if (flags & WRITE_STRING_FILE_DISABLE_BUFFER)
+                setvbuf(f, NULL, _IONBF, 0);
+
         r = write_string_stream_ts(f, line, flags, ts);
         if (r < 0)
                 goto fail;
diff --git a/src/basic/fileio.h b/src/basic/fileio.h
index c283f41f09b..da5d5c66b51 100644
--- a/src/basic/fileio.h
+++ b/src/basic/fileio.h
@@ -35,6 +35,7 @@ typedef enum {
         WRITE_STRING_FILE_AVOID_NEWLINE     = 1<<2,
         WRITE_STRING_FILE_VERIFY_ON_FAILURE = 1<<3,
         WRITE_STRING_FILE_SYNC              = 1<<4,
+        WRITE_STRING_FILE_DISABLE_BUFFER    = 1<<5,
 
         /* And before you wonder, why write_string_file_atomic_label_ts() is a separate function instead of just one
            more flag here: it's about linking: we don't want to pull -lselinux into all users of write_string_file()
diff --git a/src/shared/sysctl-util.c b/src/shared/sysctl-util.c
index 391065d804a..189580e3ed2 100644
--- a/src/shared/sysctl-util.c
+++ b/src/shared/sysctl-util.c
@@ -60,7 +60,7 @@ int sysctl_write(const char *property, const char *value) {
         log_debug("Setting '%s' to '%s'", property, value);
 
         p = strjoina("/proc/sys/", property);
-        return write_string_file(p, value, 0);
+        return write_string_file(p, value, WRITE_STRING_FILE_DISABLE_BUFFER);
 }
 
 int sysctl_read(const char *property, char **content) {
diff --git a/src/sysctl/sysctl.c b/src/sysctl/sysctl.c
index 4c468d011ad..a1dc95b2bb2 100644
--- a/src/sysctl/sysctl.c
+++ b/src/sysctl/sysctl.c
@@ -106,16 +106,16 @@ static int parse_file(OrderedHashmap *sysctl_options, const char *path, bool ign
 
         log_debug("Parsing %s", path);
         for (;;) {
-                char l[LINE_MAX], *p, *value, *new_value, *property, *existing;
+                char *p, *value, *new_value, *property, *existing;
+                _cleanup_free_ char *l = NULL;
                 void *v;
                 int k;
+                k = read_line(f, LONG_LINE_MAX, &l);
+                if (k == 0)
+                        break;
 
-                if (!fgets(l, sizeof(l), f)) {
-                        if (feof(f))
-                                break;
-
-                        return log_error_errno(errno, "Failed to read file '%s', ignoring: %m", path);
-                }
+                if (k < 0)
+                        return log_error_errno(k, "Failed to read file '%s', ignoring: %m", path);
 
                 c++;