diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index d31555d..407cd57 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -130,6 +130,17 @@
 #error "MBEDTLS_ENTROPY_FORCE_SHA256 defined, but not all prerequisites"
 #endif
 
+#if defined(MBEDTLS_TEST_WO_ENTROPY)
+#warning "MBEDTLS_TEST_WO_ENTROPY defined, this build provides no security!"
+#if !defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES)
+#error "MBEDTLS_TEST_WO_ENTROPY defined, but not all prerequisites"
+#endif
+#if defined(MBEDTLS_ENTROPY_NV_SEED) || defined(MBEDTLS_ENTROPY_HARDWARE_ALT) || \
+    defined(MBEDTLS_HAVEGE_C)
+#error "MBEDTLS_TEST_WO_ENTROPY defined, but entropy sources too"
+#endif
+#endif
+
 #if defined(MBEDTLS_GCM_C) && (                                        \
         !defined(MBEDTLS_AES_C) && !defined(MBEDTLS_CAMELLIA_C) )
 #error "MBEDTLS_GCM_C defined, but not all prerequisites"
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 0efee04..c42b88d 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -279,6 +279,29 @@
 //#define MBEDTLS_AES_DECRYPT_ALT
 
 /**
+ * \def MBEDTLS_TEST_WO_ENTROPY
+ *
+ * Enable testing mbed TLS without access to any entropy. This enables testing
+ * the library before the platforms entropy sources are integrated (, see for
+ * example the MBEDTLS_ENTROPY_HARDWARE_ALT or the MBEDTLS_ENTROPY_NV_SEED
+ * switch).
+ *
+ * WARNING! This switch is extremely DANGEROUS, don't use it in production code
+ * under any circumstances. This switch nullifies any security provided by the
+ * library.
+ */
+//#define MBEDTLS_TEST_WO_ENTROPY
+
+
+/**
+ * \def MBEDTLS_ENTROPY_NV_SEED
+ *
+ * Strong software entropy source. It is not yet implemented,
+ * adding it because it is mutually exclusive with MBEDTLS_TEST_WO_ENTROPY.
+ */
+//#define MBEDTLS_ENTROPY_NV_SEED
+
+/**
  * \def MBEDTLS_ENTROPY_HARDWARE_ALT
  *
  * Uncomment this macro to let mbed TLS use your own implementation of a
diff --git a/include/mbedtls/entropy_poll.h b/include/mbedtls/entropy_poll.h
index dc11911..3fcfef2 100644
--- a/include/mbedtls/entropy_poll.h
+++ b/include/mbedtls/entropy_poll.h
@@ -43,6 +43,14 @@
 #define MBEDTLS_ENTROPY_MIN_HARDCLOCK     4     /**< Minimum for mbedtls_timing_hardclock()        */
 #define MBEDTLS_ENTROPY_MIN_HARDWARE     32     /**< Minimum for the hardware source */
 
+/**
+ * \brief           Entropy poll callback that provides 0 entropy.
+ */
+#if defined(MBEDTLS_TEST_WO_ENTROPY)
+    int mbedtls_zero_entropy_poll( void *data,
+                                unsigned char *output, size_t len, size_t *olen );
+#endif
+
 #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
 /**
  * \brief           Platform-specific entropy poll callback