--- a/libblkid-tiny/libblkid-tiny.c
+++ b/libblkid-tiny/libblkid-tiny.c
@@ -282,7 +282,7 @@ int probe_block(char *block, struct blki
 
 		mag = &idinfos[i]->magics[0];
 
-		while (mag->magic) {
+		while (mag && mag->magic) {
 			int off = (mag->kboff * 1024) + mag->sboff;
 			char magic[32] = { 0 };