diff --git a/tests/crypto/secp256r1/mbedtls.conf b/tests/crypto/secp256r1/mbedtls.conf
index bbc2eb0e656..c4ea620de55 100644
--- a/tests/crypto/secp256r1/mbedtls.conf
+++ b/tests/crypto/secp256r1/mbedtls.conf
@@ -1,6 +1,7 @@
 CONFIG_MBEDTLS=y
 CONFIG_MBEDTLS_PSA_CRYPTO_C=y
 CONFIG_MBEDTLS_PSA_P256M_DRIVER_ENABLED=y
+CONFIG_MBEDTLS_PSA_STATIC_KEY_SLOT_BUFFER_SIZE=65
 CONFIG_MBEDTLS_PSA_STATIC_KEY_SLOTS=y
 CONFIG_MBEDTLS_PSA_KEY_SLOT_COUNT=2