diff --git a/samples/cellular/https_client/overlay-tfm_mbedtls.conf b/samples/cellular/https_client/overlay-tfm_mbedtls.conf
index 008df5db04d9..b488f1f4de5d 100644
--- a/samples/cellular/https_client/overlay-tfm_mbedtls.conf
+++ b/samples/cellular/https_client/overlay-tfm_mbedtls.conf
@@ -12,6 +12,7 @@ CONFIG_MBEDTLS_SSL_OUT_CONTENT_LEN=4096
 CONFIG_MBEDTLS_HEAP_SIZE=32768
 CONFIG_MBEDTLS_TLS_LIBRARY=y
 CONFIG_MBEDTLS_X509_LIBRARY=y
+CONFIG_MBEDTLS_RSA_C=y
 CONFIG_MBEDTLS_PKCS1_V15=y
 CONFIG_NRF_SECURITY_ADVANCED=y
 CONFIG_NORDIC_SECURITY_BACKEND=y