diff --git a/tests/suites/test_suite_hkdf.data b/tests/suites/test_suite_hkdf.data
index cdf602a..1583736 100644
--- a/tests/suites/test_suite_hkdf.data
+++ b/tests/suites/test_suite_hkdf.data
@@ -1,3 +1,18 @@
+HKDF extract fails with hash_len of 0
+test_hkdf_extract_ret:0:MBEDTLS_ERR_HKDF_BAD_INPUT_DATA
+
+HKDF expand fails with NULL okm
+test_hkdf_expand_ret:32:32:0:MBEDTLS_ERR_HKDF_BAD_INPUT_DATA
+
+HKDF expand fails with hash_len of 0
+test_hkdf_expand_ret:0:32:32:MBEDTLS_ERR_HKDF_BAD_INPUT_DATA
+
+HKDF expand fails with prk_len < hash_len
+test_hkdf_expand_ret:32:16:32:MBEDTLS_ERR_HKDF_BAD_INPUT_DATA
+
+HKDF expand fails with okm_len / hash_len > 255
+test_hkdf_expand_ret:32:32:8192:MBEDTLS_ERR_HKDF_BAD_INPUT_DATA
+
 HKDF RFC5869 Test Vector #1
 depends_on:MBEDTLS_SHA256_C
 test_hkdf:6:"0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b":"000102030405060708090a0b0c":"f0f1f2f3f4f5f6f7f8f9":"3cb25f25faacd57a90434f64d0362f2a2d2d0a90cf1a5a4c5db02d56ecc4c5bf34007208d5b887185865"
diff --git a/tests/suites/test_suite_hkdf.function b/tests/suites/test_suite_hkdf.function
index f38545c..c85a51a 100644
--- a/tests/suites/test_suite_hkdf.function
+++ b/tests/suites/test_suite_hkdf.function
@@ -1,5 +1,6 @@
 /* BEGIN_HEADER */
 #include "mbedtls/hkdf.h"
+#include "mbedtls/md_internal.h"
 /* END_HEADER */
 
 /* BEGIN_DEPENDENCIES
@@ -108,3 +109,62 @@
     mbedtls_free(output_okm);
 }
 /* END_CASE */
+
+/* BEGIN_CASE */
+void test_hkdf_extract_ret( int hash_len, int ret )
+{
+    int output_ret;
+    unsigned char *salt = NULL;
+    unsigned char *ikm = NULL;
+    unsigned char *prk = NULL;
+    size_t salt_len, ikm_len;
+    struct mbedtls_md_info_t fake_md_info;
+
+    memset( &fake_md_info, 0, sizeof( fake_md_info ) );
+    fake_md_info.type = MBEDTLS_MD_NONE;
+    fake_md_info.size = hash_len;
+
+    prk = mbedtls_calloc( MBEDTLS_MD_MAX_SIZE, 1 );
+    salt_len = 0;
+    ikm_len = 0;
+
+    output_ret = mbedtls_hkdf_extract( &fake_md_info, salt, salt_len,
+                                       ikm, ikm_len, prk );
+    TEST_ASSERT( output_ret == ret );
+
+exit:
+    mbedtls_free(prk);
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void test_hkdf_expand_ret( int hash_len, int prk_len, int okm_len, int ret )
+{
+    int output_ret;
+    unsigned char *info = NULL;
+    unsigned char *prk = NULL;
+    unsigned char *okm = NULL;
+    size_t info_len;
+    struct mbedtls_md_info_t fake_md_info;
+
+    memset( &fake_md_info, 0, sizeof( fake_md_info ) );
+    fake_md_info.type = MBEDTLS_MD_NONE;
+    fake_md_info.size = hash_len;
+
+    info_len = 0;
+
+    if (prk_len > 0)
+        prk = mbedtls_calloc( prk_len, 1 );
+
+    if (okm_len > 0)
+        okm = mbedtls_calloc( okm_len, 1 );
+
+    output_ret = mbedtls_hkdf_expand( &fake_md_info, prk, prk_len,
+                                      info, info_len, okm, okm_len );
+    TEST_ASSERT( output_ret == ret );
+
+exit:
+    mbedtls_free(prk);
+    mbedtls_free(okm);
+}
+/* END_CASE */