diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index fab59a60b..786fa3d90 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -369,6 +369,7 @@ if (DEFINED LWS_PLAT_UNIX)
 endif()
 set(LWS_HAVE_MBEDTLS_NET_SOCKETS ${LWS_HAVE_MBEDTLS_NET_SOCKETS} PARENT_SCOPE)
 set(LWS_HAVE_MBEDTLS_SSL_NEW_SESSION_TICKET ${LWS_HAVE_MBEDTLS_SSL_NEW_SESSION_TICKET} PARENT_SCOPE)
+set(LWS_HAVE_mbedtls_ssl_conf_alpn_protocols ${LWS_HAVE_mbedtls_ssl_conf_alpn_protocols} PARENT_SCOPE)
 set(TEST_SERVER_SSL_KEY "${TEST_SERVER_SSL_KEY}" PARENT_SCOPE)
 set(TEST_SERVER_SSL_CERT "${TEST_SERVER_SSL_CERT}" PARENT_SCOPE)
 set(TEST_SERVER_DATA ${TEST_SERVER_DATA} PARENT_SCOPE)
diff --git a/lib/tls/CMakeLists.txt b/lib/tls/CMakeLists.txt
index e7ab5e002..c0014509a 100644
--- a/lib/tls/CMakeLists.txt
+++ b/lib/tls/CMakeLists.txt
@@ -399,7 +399,8 @@ if (LWS_WITH_MBEDTLS)
 	else()
 		CHECK_C_SOURCE_COMPILES("#include <mbedtls/x509_crt.h>\nint main(void) { struct mbedtls_x509_crt c; c.authority_key_id.keyIdentifier.tag = MBEDTLS_ASN1_OCTET_STRING; return c.authority_key_id.keyIdentifier.tag; }\n" LWS_HAVE_MBEDTLS_AUTH_KEY_ID)
 		CHECK_C_SOURCE_COMPILES("#include <mbedtls/ssl.h>\nint main(void) { void *v = (void *)mbedtls_ssl_set_verify; return !!v; }\n" LWS_HAVE_mbedtls_ssl_set_verify)
-		CHECK_SYMBOL_EXISTS(mbedtls_ssl_conf_alpn_protocols LWS_HAVE_mbedtls_ssl_conf_alpn_protocols PARENT_SCOPE)
+		CHECK_C_SOURCE_COMPILES("#include <mbedtls/ssl.h>\nint main(void) { void *v = (void *)mbedtls_ssl_conf_alpn_protocols; return !!v; }\n" LWS_HAVE_mbedtls_ssl_conf_alpn_protocols)
+
 		CHECK_FUNCTION_EXISTS(mbedtls_ssl_get_alpn_protocol LWS_HAVE_mbedtls_ssl_get_alpn_protocol PARENT_SCOPE)
 		CHECK_FUNCTION_EXISTS(mbedtls_ssl_conf_sni LWS_HAVE_mbedtls_ssl_conf_sni PARENT_SCOPE)
 		CHECK_FUNCTION_EXISTS(mbedtls_ssl_set_hs_ca_chain LWS_HAVE_mbedtls_ssl_set_hs_ca_chain PARENT_SCOPE)
@@ -569,6 +570,7 @@ endif()
 exports_to_parent_scope()
 set(LWS_HAVE_MBEDTLS_NET_SOCKETS ${LWS_HAVE_MBEDTLS_NET_SOCKETS} PARENT_SCOPE)
 set(LWS_HAVE_MBEDTLS_SSL_NEW_SESSION_TICKET ${LWS_HAVE_MBEDTLS_SSL_NEW_SESSION_TICKET} PARENT_SCOPE)
+set(LWS_HAVE_mbedtls_ssl_conf_alpn_protocols ${LWS_HAVE_mbedtls_ssl_conf_alpn_protocols} PARENT_SCOPE)
 set(TEST_SERVER_SSL_KEY "${TEST_SERVER_SSL_KEY}" PARENT_SCOPE)
 set(TEST_SERVER_SSL_CERT "${TEST_SERVER_SSL_CERT}" PARENT_SCOPE)
 set(TEST_SERVER_DATA ${TEST_SERVER_DATA} PARENT_SCOPE)