diff --git a/prog/sensors/main.c b/prog/sensors/main.c
index da012c8b..0113680e 100644
--- a/prog/sensors/main.c
+++ b/prog/sensors/main.c
@@ -405,7 +405,7 @@ void do_a_print(sensors_chip_name name)
 	    break;
 	}
     }
-    if(m == NULL)
+    if(m->prefix == NULL)
 	print_unknown_chip(&name);
   }
   printf("\n");