diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index c4a48f8..35d71e7 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -6684,22 +6684,17 @@
                                         const uint8_t *data,
                                         size_t data_length)
 {
-    if (pbkdf2->state != PSA_PBKDF2_STATE_INPUT_COST_SET &&
-        pbkdf2->state != PSA_PBKDF2_STATE_SALT_SET) {
+    if (pbkdf2->state == PSA_PBKDF2_STATE_INPUT_COST_SET) {
+        pbkdf2->state = PSA_PBKDF2_STATE_SALT_SET;
+    } else if (pbkdf2->state == PSA_PBKDF2_STATE_SALT_SET) {
+        /* Appending to existing salt. No state change. */
+    } else {
         return PSA_ERROR_BAD_STATE;
     }
 
     if (data_length == 0) {
-        /* Nothing to do */
-    } else if (pbkdf2->state == PSA_PBKDF2_STATE_INPUT_COST_SET) {
-        pbkdf2->salt = mbedtls_calloc(1, data_length);
-        if (pbkdf2->salt == NULL) {
-            return PSA_ERROR_INSUFFICIENT_MEMORY;
-        }
-
-        memcpy(pbkdf2->salt, data, data_length);
-        pbkdf2->salt_length = data_length;
-    } else if (pbkdf2->state == PSA_PBKDF2_STATE_SALT_SET) {
+        /* Appending an empty string, nothing to do. */
+    } else {
         uint8_t *next_salt;
 
         next_salt = mbedtls_calloc(1, data_length + pbkdf2->salt_length);
@@ -6707,15 +6702,14 @@
             return PSA_ERROR_INSUFFICIENT_MEMORY;
         }
 
-        memcpy(next_salt, pbkdf2->salt, pbkdf2->salt_length);
+        if (pbkdf2->salt_length != 0) {
+            memcpy(next_salt, pbkdf2->salt, pbkdf2->salt_length);
+        }
         memcpy(next_salt + pbkdf2->salt_length, data, data_length);
         pbkdf2->salt_length += data_length;
         mbedtls_free(pbkdf2->salt);
         pbkdf2->salt = next_salt;
     }
-
-    pbkdf2->state = PSA_PBKDF2_STATE_SALT_SET;
-
     return PSA_SUCCESS;
 }
 
diff --git a/tests/suites/test_suite_psa_crypto.data b/tests/suites/test_suite_psa_crypto.data
index 410ae64..2237a41 100644
--- a/tests/suites/test_suite_psa_crypto.data
+++ b/tests/suites/test_suite_psa_crypto.data
@@ -6377,10 +6377,22 @@
 depends_on:PSA_WANT_ALG_PBKDF2_HMAC:PSA_WANT_ALG_SHA_1
 derive_output:PSA_ALG_PBKDF2_HMAC(PSA_ALG_SHA_1):PSA_KEY_DERIVATION_INPUT_COST:"1000":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_SALT:"7361006c74":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_PASSWORD:"7061737300776f7264":PSA_SUCCESS:0:"":PSA_SUCCESS:"":16:"56fa6aa75548099dcc37d7f03425e0c3":"":0:1:0
 
-PSA key derivation: PBKDF2-HMAC(SHA-256), RFC7914 #1, salt in two step
+PSA key derivation: PBKDF2-HMAC(SHA-256), RFC7914 #1, salt=2+2
 depends_on:PSA_WANT_ALG_PBKDF2_HMAC:PSA_WANT_ALG_SHA_256
 derive_output:PSA_ALG_PBKDF2_HMAC(PSA_ALG_SHA_256):PSA_KEY_DERIVATION_INPUT_COST:"01":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_SALT:"7361":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_SALT:"6c74":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_PASSWORD:"706173737764":PSA_SUCCESS:"":64:"55ac046e56e3089fec1691c22544b605f94185216dde0465e68b9d57c20dacbc49ca9cccf179b645991664b39d77ef317c71b845b1e30bd509112041d3a19783":"":0:1:0
 
+PSA key derivation: PBKDF2-HMAC(SHA-256), RFC7914 #1, salt=0+4
+depends_on:PSA_WANT_ALG_PBKDF2_HMAC:PSA_WANT_ALG_SHA_256
+derive_output:PSA_ALG_PBKDF2_HMAC(PSA_ALG_SHA_256):PSA_KEY_DERIVATION_INPUT_COST:"01":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_SALT:"":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_SALT:"73616c74":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_PASSWORD:"706173737764":PSA_SUCCESS:"":64:"55ac046e56e3089fec1691c22544b605f94185216dde0465e68b9d57c20dacbc49ca9cccf179b645991664b39d77ef317c71b845b1e30bd509112041d3a19783":"":0:1:0
+
+PSA key derivation: PBKDF2-HMAC(SHA-256), RFC7914 #1, salt=4+0
+depends_on:PSA_WANT_ALG_PBKDF2_HMAC:PSA_WANT_ALG_SHA_256
+derive_output:PSA_ALG_PBKDF2_HMAC(PSA_ALG_SHA_256):PSA_KEY_DERIVATION_INPUT_COST:"01":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_SALT:"73616c74":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_SALT:"":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_PASSWORD:"706173737764":PSA_SUCCESS:"":64:"55ac046e56e3089fec1691c22544b605f94185216dde0465e68b9d57c20dacbc49ca9cccf179b645991664b39d77ef317c71b845b1e30bd509112041d3a19783":"":0:1:0
+
+PSA key derivation: PBKDF2-HMAC(SHA-256), salt=0+0
+depends_on:PSA_WANT_ALG_PBKDF2_HMAC:PSA_WANT_ALG_SHA_256
+derive_output:PSA_ALG_PBKDF2_HMAC(PSA_ALG_SHA_256):PSA_KEY_DERIVATION_INPUT_COST:"01":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_SALT:"":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_SALT:"":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_PASSWORD:"706173737764":PSA_SUCCESS:"":64:"b03ada2451aa1084ce14cf51c93eeea9d2bd435db3f93a70031b2de39fdef45d2ccb1fe2078e79773c148311d3e6ec5dec9da7f30d78584ec21c94de839671b2":"":0:1:0
+
 PSA key derivation: PBKDF2-HMAC(SHA-256), RFC7914 #1, password as key, derive key
 depends_on:PSA_WANT_ALG_PBKDF2_HMAC:PSA_WANT_ALG_SHA_256
 derive_output:PSA_ALG_PBKDF2_HMAC(PSA_ALG_SHA_256):PSA_KEY_DERIVATION_INPUT_COST:"01":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_SALT:"73616c74":PSA_SUCCESS:PSA_KEY_DERIVATION_INPUT_PASSWORD:"706173737764":PSA_SUCCESS:0:"":PSA_SUCCESS:"":64:"55ac046e56e3089fec1691c22544b605f94185216dde0465e68b9d57c20dacbc49ca9cccf179b645991664b39d77ef317c71b845b1e30bd509112041d3a19783":"":0:1:1