diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 1dc9648..30be676 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -1070,7 +1070,7 @@
     if( ssl->conf->psk_opaque != 0 )
         return( ssl->conf->psk_opaque );
 
-    return( 0 );
+    return( PSA_KEY_HANDLE_INIT );
 }
 #endif /* MBEDTLS_USE_PSA_CRYPTO */
 
diff --git a/include/psa/crypto_platform.h b/include/psa/crypto_platform.h
index c64f61d..6ada324 100644
--- a/include/psa/crypto_platform.h
+++ b/include/psa/crypto_platform.h
@@ -51,6 +51,7 @@
 
 /* Integral type representing a key handle. */
 typedef uint16_t psa_key_handle_t;
+#define PSA_KEY_HANDLE_INIT ( (psa_key_handle_t)0 )
 
 #if defined(MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER)