diff --git a/examples/ReadWrite/ReadWrite.ino b/examples/ReadWrite/ReadWrite.ino
index d964668..1a9ba66 100644
--- a/examples/ReadWrite/ReadWrite.ino
+++ b/examples/ReadWrite/ReadWrite.ino
@@ -34,9 +34,14 @@ void setup() {
   Serial.print("Initializing SD card...");
 
   if (!SD.begin(4)) {
-    Serial.println("initialization failed!");
+    Serial.println("initialization failed. Things to check:");
+    Serial.println("1. is a card inserted?");
+    Serial.println("2. is your wiring correct?");
+    Serial.println("3. did you change the chipSelect pin to match your shield or module?");
+    Serial.println("Note: press reset or reopen this serial monitor after fixing your issue!");
     while (1);
   }
+
   Serial.println("initialization done.");
 
   // open the file. note that only one file can be open at a time,
diff --git a/src/utility/SdFat.h b/src/utility/SdFat.h
index e57974d..46b880b 100644
--- a/src/utility/SdFat.h
+++ b/src/utility/SdFat.h
@@ -41,17 +41,17 @@ class SdVolume;
 // SdFile class
 
 #ifdef O_RDONLY //ARDUINO_ARCH_MBED
-#undef O_READ
-#undef O_RDONLY
-#undef O_WRITE
-#undef O_WRONLY
-#undef O_RDWR
-#undef O_ACCMODE
-#undef O_APPEND
-#undef O_SYNC
-#undef O_CREAT
-#undef O_EXCL
-#undef O_TRUNC
+  #undef O_READ
+  #undef O_RDONLY
+  #undef O_WRITE
+  #undef O_WRONLY
+  #undef O_RDWR
+  #undef O_ACCMODE
+  #undef O_APPEND
+  #undef O_SYNC
+  #undef O_CREAT
+  #undef O_EXCL
+  #undef O_TRUNC
 #endif
 
 // flags for ls()