Fix typo in platform macro defines for examples
diff --git a/programs/util/pem2der.c b/programs/util/pem2der.c
index fda5f57..73a9fb5 100644
--- a/programs/util/pem2der.c
+++ b/programs/util/pem2der.c
@@ -33,7 +33,7 @@
 #define mbedtls_free            free
 #define mbedtls_calloc          calloc
 #define mbedtls_printf          printf
-#define MBEDTLS_EXTI_SUCCESS    EXIT_SUCCESS
+#define MBEDTLS_EXIT_SUCCESS    EXIT_SUCCESS
 #define MBEDTLS_EXIT_FAILURE    EXIT_FAILURE
 #endif /* MBEDTLS_PLATFORM_C */