diff --git a/CHANGES b/CHANGES
index 5f9811a..8a0a3b3 100644
--- a/CHANGES
+++ b/CHANGES
@@ -25,6 +25,9 @@ Corrections:
 	Filan: If IP protocol type cannot be retrieved, display at least the
 	socket type
 
+	Filan: Fixed diag_set() call in filan_main.c, bug popped up with C23.
+	Thanks to Cristian Rodríguez from openSUSE for reporting this issue.
+
 Coding:
 	New Environment variable SOCAT_TRANSFER_WAIT that Socat sleep before
 	starting the data transfer loop. Useful, e.g., to accumulate multiple
diff --git a/filan_main.c b/filan_main.c
index f386937..24dd5e9 100644
--- a/filan_main.c
+++ b/filan_main.c
@@ -32,7 +32,7 @@ int main(int argc, const char *argv[]) {
    const char *outfname = NULL;
    unsigned long fildes;
 
-   diag_set('I', false);
+   diag_set('I', NULL);
    diag_set('p', strchr(argv[0], '/') ? strrchr(argv[0], '/')+1 : argv[0]);
 
    arg1 = argv+1;  --argc;