diff --git a/cap/zx297520v3/src/lynq/lib/liblynq-sim/src/lynq_sim.cpp b/cap/zx297520v3/src/lynq/lib/liblynq-sim/src/lynq_sim.cpp
index aa69974..75a1d0b 100755
--- a/cap/zx297520v3/src/lynq/lib/liblynq-sim/src/lynq_sim.cpp
+++ b/cap/zx297520v3/src/lynq/lib/liblynq-sim/src/lynq_sim.cpp
@@ -457,6 +457,10 @@
     }
     if(puk == NULL || pin == NULL)
         return -1;
+
+    if(strlen(puk) < 4 || strlen(pin) < 4){
+        return -1;
+    }
     Parcel p;
     int res = lynq_send_common_request(&p,RIL_REQUEST_ENTER_SIM_PUK,2,1,"%s %s\n", puk, pin);
     if(res != 0)