diff --git a/tools/Diagnostics/Diagnostics.ino b/tools/Diagnostics/Diagnostics.ino
index 0f85740..2ef7f67 100644
--- a/tools/Diagnostics/Diagnostics.ino
+++ b/tools/Diagnostics/Diagnostics.ino
@@ -10,7 +10,7 @@
  **************************************************************/
 
 // Select your modem:
-// #define TINY_GSM_MODEM_SIM800
+#define TINY_GSM_MODEM_SIM800
 // #define TINY_GSM_MODEM_SIM808
 // #define TINY_GSM_MODEM_SIM868
 // #define TINY_GSM_MODEM_SIM900