diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 3019522..8f41641 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -7449,12 +7449,25 @@
     void (* entropy_init)(mbedtls_entropy_context *ctx),
     void (* entropy_free)(mbedtls_entropy_context *ctx))
 {
+    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
+
+#if defined(MBEDTLS_THREADING_C)
+    mbedtls_mutex_lock(&mbedtls_threading_psa_rngdata_mutex);
+#endif /* defined(MBEDTLS_THREADING_C) */
+
     if (global_data.rng_state != RNG_NOT_INITIALIZED) {
-        return PSA_ERROR_BAD_STATE;
+        status = PSA_ERROR_BAD_STATE;
+    } else {
+        global_data.rng.entropy_init = entropy_init;
+        global_data.rng.entropy_free = entropy_free;
+        status = PSA_SUCCESS;
     }
-    global_data.rng.entropy_init = entropy_init;
-    global_data.rng.entropy_free = entropy_free;
-    return PSA_SUCCESS;
+
+#if defined(MBEDTLS_THREADING_C)
+    mbedtls_mutex_unlock(&mbedtls_threading_psa_rngdata_mutex);
+#endif /* defined(MBEDTLS_THREADING_C) */
+
+    return status;
 }
 #endif /* !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) */