diff --git a/shared/nm-glib-aux/nm-logging-fwd.h b/shared/nm-glib-aux/nm-logging-fwd.h
index 900dfff81..693803f9d 100644
--- a/shared/nm-glib-aux/nm-logging-fwd.h
+++ b/shared/nm-glib-aux/nm-logging-fwd.h
@@ -110,4 +110,21 @@ void _nm_log_impl (const char *file,
                    const char *fmt,
                    ...) _nm_printf (10, 11);
 
+static inline NMLogLevel
+nm_log_level_from_syslog (int syslog_level)
+{
+	switch (syslog_level) {
+	case 0 /* LOG_EMERG */   : return LOGL_ERR;
+	case 1 /* LOG_ALERT */   : return LOGL_ERR;
+	case 2 /* LOG_CRIT */    : return LOGL_ERR;
+	case 3 /* LOG_ERR */     : return LOGL_ERR;
+	case 4 /* LOG_WARNING */ : return LOGL_WARN;
+	case 5 /* LOG_NOTICE */  : return LOGL_INFO;
+	case 6 /* LOG_INFO */    : return LOGL_DEBUG;
+	case 7 /* LOG_DEBUG */   : return LOGL_TRACE;
+	default:
+		return syslog_level >= 0 ? LOGL_TRACE : LOGL_ERR;
+	}
+}
+
 #endif /* __NM_LOGGING_DEFINES_H__ */
diff --git a/shared/systemd/sd-adapt-shared/nm-sd-adapt-shared.h b/shared/systemd/sd-adapt-shared/nm-sd-adapt-shared.h
index a285c3cdc..d38a39b15 100644
--- a/shared/systemd/sd-adapt-shared/nm-sd-adapt-shared.h
+++ b/shared/systemd/sd-adapt-shared/nm-sd-adapt-shared.h
@@ -21,8 +21,6 @@
 
 #include "nm-default.h"
 
-#include <syslog.h>
-
 #include "nm-glib-aux/nm-logging-fwd.h"
 
 /*****************************************************************************/
@@ -32,32 +30,18 @@
 
 /*****************************************************************************/
 
-static inline NMLogLevel
-_slog_level_to_nm (int slevel)
-{
-	switch (LOG_PRI (slevel)) {
-	case LOG_DEBUG:   return LOGL_DEBUG;
-	case LOG_WARNING: return LOGL_WARN;
-	case LOG_CRIT:
-	case LOG_ERR:     return LOGL_ERR;
-	case LOG_INFO:
-	case LOG_NOTICE:
-	default:          return LOGL_INFO;
-	}
-}
-
 static inline int
 _nm_log_get_max_level_realm (void)
 {
 	/* inline function, to avoid coverity warning about constant expression. */
-	return LOG_DEBUG;
+	return 7 /* LOG_DEBUG */;
 }
 #define log_get_max_level_realm(realm) _nm_log_get_max_level_realm ()
 
 #define log_internal_realm(level, error, file, line, func, format, ...) \
 ({ \
 	const int _nm_e = (error); \
-	const NMLogLevel _nm_l = _slog_level_to_nm ((level)); \
+	const NMLogLevel _nm_l = nm_log_level_from_syslog (LOG_PRI (level)); \
 	\
 	if (_nm_log_enabled_impl (!(NM_THREAD_SAFE_ON_MAIN_THREAD), _nm_l, LOGD_SYSTEMD)) { \
 		const char *_nm_location = strrchr ((""file), '/'); \
diff --git a/src/nm-logging.c b/src/nm-logging.c
index 48e51421b..79e3658ab 100644
--- a/src/nm-logging.c
+++ b/src/nm-logging.c
@@ -68,6 +68,15 @@
 
 /*****************************************************************************/
 
+G_STATIC_ASSERT (LOG_EMERG   == 0);
+G_STATIC_ASSERT (LOG_ALERT   == 1);
+G_STATIC_ASSERT (LOG_CRIT    == 2);
+G_STATIC_ASSERT (LOG_ERR     == 3);
+G_STATIC_ASSERT (LOG_WARNING == 4);
+G_STATIC_ASSERT (LOG_NOTICE  == 5);
+G_STATIC_ASSERT (LOG_INFO    == 6);
+G_STATIC_ASSERT (LOG_DEBUG   == 7);
+
 /* We have more then 32 logging domains. Assert that it compiles to a 64 bit sized enum */
 G_STATIC_ASSERT (sizeof (NMLogDomain) >= sizeof (guint64));