diff --git a/src/logging.c b/src/logging.c
index 2a8bfdc8d..d32ca43a7 100644
--- a/src/logging.c
+++ b/src/logging.c
@@ -336,6 +336,11 @@ err:
  * which should never happen unless even the DLGLOBAL category is missing. */
 static inline int map_subsys(int subsys)
 {
+	/* Note: comparing signed and unsigned integers */
+
+	if (subsys > 0 && ((unsigned int)subsys) >= osmo_log_info->num_cat_user)
+		subsys = DLGLOBAL;
+
 	if (subsys < 0)
 		subsys = subsys_lib2index(subsys);
 
diff --git a/tests/logging/logging_test.err b/tests/logging/logging_test.err
index f4e9c1f43..4527d8351 100644
--- a/tests/logging/logging_test.err
+++ b/tests/logging/logging_test.err
@@ -4,4 +4,5 @@ DRLL You should see this
 DLGLOBAL You should see this on DLGLOBAL (a)
 DLGLOBAL You should see this on DLGLOBAL (b)
 DLGLOBAL You should see this on DLGLOBAL (c)
+DLGLOBAL You should see this on DLGLOBAL (d)
 DLGLOBAL You should see this on DLGLOBAL (e)