diff --git a/lib/mbedtls/sha256.c b/lib/mbedtls/sha256.c
index 7d456a8..59edcb5 100644
--- a/lib/mbedtls/sha256.c
+++ b/lib/mbedtls/sha256.c
@@ -12,6 +12,10 @@
 
 #include <mbedtls/md.h>
 
+#if CONFIG_IS_ENABLED(HKDF_MBEDTLS)
+#include <mbedtls/hkdf.h>
+#endif
+
 const u8 sha256_der_prefix[SHA256_DER_LEN] = {
 	0x30, 0x31, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86,
 	0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05,
@@ -48,3 +52,22 @@
 
 	return mbedtls_md_hmac(md, key, keylen, input, ilen, output);
 }
+
+#if CONFIG_IS_ENABLED(HKDF_MBEDTLS)
+int sha256_hkdf(const unsigned char *salt, int saltlen,
+		const unsigned char *ikm, int ikmlen,
+		const unsigned char *info, int infolen,
+		unsigned char *output, int outputlen)
+{
+	const mbedtls_md_info_t *md;
+
+	md = mbedtls_md_info_from_type(MBEDTLS_MD_SHA256);
+	if (!md)
+		return MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE;
+
+	return mbedtls_hkdf(md, salt, saltlen,
+			    ikm, ikmlen,
+			    info, infolen,
+			    output, outputlen);
+}
+#endif