diff --git a/configure.ac b/configure.ac
index 7d5750c922..30c881f3fc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -218,6 +218,8 @@ AS_HELP_STRING([--without-ssl], [build without any TLS library]),[
   OPT_OPENSSL=$withval
   if test X"$withval" != Xno; then
     TLSCHOICE="${TLSCHOICE:+$TLSCHOICE, }OpenSSL"
+  else
+    SSL_DISABLED="D"
   fi
 ])
 
@@ -1955,11 +1957,11 @@ if test "x$curl_cv_native_windows" = "xyes" &&
   LIBS="-lbcrypt $LIBS"
 fi
 
-case "x$OPENSSL_ENABLED$GNUTLS_ENABLED$NSS_ENABLED$MBEDTLS_ENABLED$WOLFSSL_ENABLED$SCHANNEL_ENABLED$SECURETRANSPORT_ENABLED$BEARSSL_ENABLED$RUSTLS_ENABLED"
+case "x$OPENSSL_ENABLED$GNUTLS_ENABLED$NSS_ENABLED$MBEDTLS_ENABLED$WOLFSSL_ENABLED$SCHANNEL_ENABLED$SECURETRANSPORT_ENABLED$BEARSSL_ENABLED$RUSTLS_ENABLED$SSL_DISABLED"
 in
 x)
-  AC_MSG_WARN([SSL disabled, you will not be able to use HTTPS, FTPS, NTLM and more.])
-  AC_MSG_WARN([Use --with-openssl, --with-gnutls, --with-wolfssl, --with-mbedtls, --with-nss, --with-schannel, --with-secure-transport, --with-amissl, --with-bearssl or --with-rustls to address this.])
+  AC_MSG_ERROR([TLS not detected, you will not be able to use HTTPS, FTPS, NTLM and more.
+Use --with-openssl, --with-gnutls, --with-wolfssl, --with-mbedtls, --with-nss, --with-schannel, --with-secure-transport, --with-amissl, --with-bearssl or --with-rustls to address this.])
   ;;
 x1)
   # one SSL backend is enabled
@@ -1967,6 +1969,9 @@ x1)
   SSL_ENABLED="1"
   AC_MSG_NOTICE([built with one SSL backend])
   ;;
+xD)
+  # explicitly built without TLS
+  ;;
 *)
   # more than one SSL backend is enabled
   AC_SUBST(SSL_ENABLED)