diff -Nur a/src/exports.cc b/src/exports.cc
--- a/src/exports.cc	2024-04-02 16:52:22.374784248 +0800
+++ b/src/exports.cc	2024-04-02 16:54:11.808370595 +0800
@@ -165,8 +165,12 @@
 {
 	ostream &out = *outStream;
 
-	char *headerFn = strdup( exportHeaderFn );
-	char *suffix = strstr( headerFn, ".pack" );
+	char *headerFn = NULL;
+	char *suffix = NULL;
+	if (exportHeaderFn != 0) {
+	        headerFn = strdup( exportHeaderFn );
+	        suffix = strstr( headerFn, ".pack" );
+	}
 	if ( suffix != 0 && strcmp( suffix, ".pack" ) == 0 )
 		*suffix = 0;