diff --git a/library/entropy.c b/library/entropy.c
index 1a7b9ab..49710de 100644
--- a/library/entropy.c
+++ b/library/entropy.c
@@ -27,6 +27,12 @@
 
 #if defined(MBEDTLS_ENTROPY_C)
 
+#if defined(MBEDTLS_TEST_NULL_ENTROPY)
+#warning "**** WARNING!  MBEDTLS_TEST_NULL_ENTROPY defined! ****"
+#warning "**** THIS BUILD HAS NO DEFINED ENTROPY SOURCES    ****"
+#warning "**** NOT SUITABLE FOR PRODUCTION                  ****"
+#endif
+
 #include "mbedtls/entropy.h"
 #include "mbedtls/entropy_poll.h"
 
@@ -73,7 +79,7 @@
     mbedtls_havege_init( &ctx->havege_data );
 #endif
 
-#if defined(MBEDTLS_TEST_WO_ENTROPY)
+#if defined(MBEDTLS_TEST_NULL_ENTROPY)
     mbedtls_entropy_add_source( ctx, mbedtls_zero_entropy_poll, NULL,
                                 1, MBEDTLS_ENTROPY_SOURCE_STRONG );
 #endif
diff --git a/library/entropy_poll.c b/library/entropy_poll.c
index 1ddbdc7..ed80bab 100644
--- a/library/entropy_poll.c
+++ b/library/entropy_poll.c
@@ -191,11 +191,12 @@
 #endif /* _WIN32 && !EFIX64 && !EFI32 */
 #endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */
 
-#if defined(MBEDTLS_TEST_WO_ENTROPY)
+#if defined(MBEDTLS_TEST_NULL_ENTROPY)
 int mbedtls_zero_entropy_poll( void *data,
                     unsigned char *output, size_t len, size_t *olen )
 {
     ((void) data);
+    ((void) output);
     *olen = 0;
 
     if( len < sizeof(unsigned char) )
diff --git a/library/version_features.c b/library/version_features.c
index a00ae27..37b30a9 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -159,9 +159,9 @@
 #if defined(MBEDTLS_AES_DECRYPT_ALT)
     "MBEDTLS_AES_DECRYPT_ALT",
 #endif /* MBEDTLS_AES_DECRYPT_ALT */
-#if defined(MBEDTLS_TEST_WO_ENTROPY)
-    "MBEDTLS_TEST_WO_ENTROPY",
-#endif /* MBEDTLS_TEST_WO_ENTROPY */
+#if defined(MBEDTLS_TEST_NULL_ENTROPY)
+    "MBEDTLS_TEST_NULL_ENTROPY",
+#endif /* MBEDTLS_TEST_NULL_ENTROPY */
 #if defined(MBEDTLS_ENTROPY_NV_SEED)
     "MBEDTLS_ENTROPY_NV_SEED",
 #endif /* MBEDTLS_ENTROPY_NV_SEED */