diff --git a/modules/mbedtls/configs/config-tls-generic.h b/modules/mbedtls/configs/config-tls-generic.h
index 80e9d11e90c..92471768b6c 100644
--- a/modules/mbedtls/configs/config-tls-generic.h
+++ b/modules/mbedtls/configs/config-tls-generic.h
@@ -369,6 +369,7 @@
 #if defined(CONFIG_MBEDTLS_PEM_CERTIFICATE_FORMAT) && \
     defined(MBEDTLS_X509_CRT_PARSE_C)
 #define MBEDTLS_PEM_PARSE_C
+#define MBEDTLS_PEM_WRITE_C
 #define MBEDTLS_BASE64_C
 #endif