diff --git a/src/libsystemd/sd-bus/bus-internal.c b/src/libsystemd/sd-bus/bus-internal.c
index 598b7f110c..dff39cb13f 100644
--- a/src/libsystemd/sd-bus/bus-internal.c
+++ b/src/libsystemd/sd-bus/bus-internal.c
@@ -97,7 +97,7 @@ bool interface_name_is_valid(const char *p) {
                         dot = false;
                 }
 
-        if (q - p > 255)
+        if (q - p > SD_BUS_MAXIMUM_NAME_LENGTH)
                 return false;
 
         if (dot)
@@ -139,7 +139,7 @@ bool service_name_is_valid(const char *p) {
                         dot = false;
                 }
 
-        if (q - p > 255)
+        if (q - p > SD_BUS_MAXIMUM_NAME_LENGTH)
                 return false;
 
         if (dot)
@@ -170,7 +170,7 @@ bool member_name_is_valid(const char *p) {
                         return false;
         }
 
-        if (q - p > 255)
+        if (q - p > SD_BUS_MAXIMUM_NAME_LENGTH)
                 return false;
 
         return true;
diff --git a/src/systemd/sd-bus.h b/src/systemd/sd-bus.h
index 311602d048..84ceb62dc7 100644
--- a/src/systemd/sd-bus.h
+++ b/src/systemd/sd-bus.h
@@ -36,6 +36,9 @@ _SD_BEGIN_DECLARATIONS;
 /* https://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-marshaling-signature */
 #define SD_BUS_MAXIMUM_SIGNATURE_LENGTH 255
 
+/* https://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names */
+#define SD_BUS_MAXIMUM_NAME_LENGTH 255
+
 /* Types */
 
 typedef struct sd_bus sd_bus;