diff --git a/library/entropy.c b/library/entropy.c
index 49710de..282640f 100644
--- a/library/entropy.c
+++ b/library/entropy.c
@@ -80,7 +80,7 @@
 #endif
 
 #if defined(MBEDTLS_TEST_NULL_ENTROPY)
-    mbedtls_entropy_add_source( ctx, mbedtls_zero_entropy_poll, NULL,
+    mbedtls_entropy_add_source( ctx, mbedtls_null_entropy_poll, NULL,
                                 1, MBEDTLS_ENTROPY_SOURCE_STRONG );
 #endif
 
diff --git a/library/entropy_poll.c b/library/entropy_poll.c
index ed80bab..a116e60 100644
--- a/library/entropy_poll.c
+++ b/library/entropy_poll.c
@@ -192,7 +192,7 @@
 #endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */
 
 #if defined(MBEDTLS_TEST_NULL_ENTROPY)
-int mbedtls_zero_entropy_poll( void *data,
+int mbedtls_null_entropy_poll( void *data,
                     unsigned char *output, size_t len, size_t *olen )
 {
     ((void) data);