diff --git a/src/basic/log.c b/src/basic/log.c
index 37a5ffa74f..ea252c4130 100644
--- a/src/basic/log.c
+++ b/src/basic/log.c
@@ -1231,16 +1231,34 @@ int log_syntax_internal(
         if (unit)
                 unit_fmt = getpid_cached() == 1 ? "UNIT=%s" : "USER_UNIT=%s";
 
-        return log_struct_internal(
-                        LOG_REALM_PLUS_LEVEL(LOG_REALM_SYSTEMD, level),
-                        error,
-                        file, line, func,
-                        "MESSAGE_ID=" SD_MESSAGE_INVALID_CONFIGURATION_STR,
-                        "CONFIG_FILE=%s", config_file,
-                        "CONFIG_LINE=%u", config_line,
-                        LOG_MESSAGE("%s:%u: %s", config_file, config_line, buffer),
-                        unit_fmt, unit,
-                        NULL);
+        if (config_file)
+                return log_struct_internal(
+                                LOG_REALM_PLUS_LEVEL(LOG_REALM_SYSTEMD, level),
+                                error,
+                                file, line, func,
+                                "MESSAGE_ID=" SD_MESSAGE_INVALID_CONFIGURATION_STR,
+                                "CONFIG_FILE=%s", config_file,
+                                "CONFIG_LINE=%u", config_line,
+                                LOG_MESSAGE("%s:%u: %s", config_file, config_line, buffer),
+                                unit_fmt, unit,
+                                NULL);
+        else if (unit)
+                return log_struct_internal(
+                                LOG_REALM_PLUS_LEVEL(LOG_REALM_SYSTEMD, level),
+                                error,
+                                file, line, func,
+                                "MESSAGE_ID=" SD_MESSAGE_INVALID_CONFIGURATION_STR,
+                                LOG_MESSAGE("%s: %s", unit, buffer),
+                                unit_fmt, unit,
+                                NULL);
+        else
+                return log_struct_internal(
+                                LOG_REALM_PLUS_LEVEL(LOG_REALM_SYSTEMD, level),
+                                error,
+                                file, line, func,
+                                "MESSAGE_ID=" SD_MESSAGE_INVALID_CONFIGURATION_STR,
+                                LOG_MESSAGE("%s", buffer),
+                                NULL);
 }
 
 int log_syntax_invalid_utf8_internal(