diff --git a/library/entropy_poll.c b/library/entropy_poll.c
index e2f45c7..79efb87 100644
--- a/library/entropy_poll.c
+++ b/library/entropy_poll.c
@@ -188,6 +188,22 @@
 #endif /* _WIN32 && !EFIX64 && !EFI32 */
 #endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */
 
+#if defined(MBEDTLS_TEST_WO_ENTROPY)
+int mbedtls_zero_entropy_poll( void *data,
+                    unsigned char *output, size_t len, size_t *olen )
+{
+    ((void) data);
+    *olen = 0;
+
+    if( len < sizeof(unsigned char) )
+        return( 0 );
+
+    *olen = sizeof(unsigned char);
+
+    return( 0 );
+}
+#endif
+
 #if defined(MBEDTLS_TIMING_C)
 int mbedtls_hardclock_poll( void *data,
                     unsigned char *output, size_t len, size_t *olen )