diff --git a/firmware/basic/uuid.c b/firmware/basic/uuid.c
index d537f75..8b903ee 100644
--- a/firmware/basic/uuid.c
+++ b/firmware/basic/uuid.c
@@ -6,18 +6,21 @@
 #include "core/iap/iap.h"
 
 uint32_t GetUUID32(void){
-    IAP_return_t iap_return;
-    iap_return = iapReadSerialNumber();
-    if (iap_return.ReturnCode == 0){
-        uint32_t block[4];
-        uint32_t k[4] = {0,0,0,0};
-        int i;
-        for(i=0; i<4; i++)
-            block[i] = iap_return.Result[i];
-        xxtea_encode_words(block, 4, k);
-        return block[0];
+    static uint32_t uuid = 0;
+    if( uuid == 0){
+        IAP_return_t iap_return;
+        iap_return = iapReadSerialNumber();
+        if (iap_return.ReturnCode == 0){
+            uint32_t block[4];
+            uint32_t k[4] = {0,0,0,0};
+            int i;
+            for(i=0; i<4; i++)
+                block[i] = iap_return.Result[i];
+            xxtea_encode_words(block, 4, k);
+            uuid = block[0];
+        }
     }
-    return 0;
+    return uuid;
 };
 
 // What OpenBeacon used. Do we want this?