diff --git a/configure.ac b/configure.ac
index 8b3ff904c1..5c697618b9 100755
--- a/configure.ac
+++ b/configure.ac
@@ -552,6 +552,10 @@ AS_HELP_STRING([--disable-ldap],[Disable LDAP support]),
        AC_DEFINE(CURL_DISABLE_LDAP, 1, [to disable LDAP])
        AC_SUBST(CURL_DISABLE_LDAP, [1])
        ;;
+  yes)
+       ldap_askedfor="yes"
+       AC_MSG_RESULT(yes)
+       ;;
   *)
        AC_MSG_RESULT(yes)
        ;;
@@ -1356,6 +1360,9 @@ if test x$CURL_DISABLE_LDAP != x1 ; then
 
   if test "$LDAPLIBNAME" ; then
     AC_CHECK_LIB("$LDAPLIBNAME", ldap_init,, [
+      if test -n "$ldap_askedfor"; then
+        AC_MSG_ERROR([couldn't detect the LDAP libraries])
+      fi
       AC_MSG_WARN(["$LDAPLIBNAME" is not an LDAP library: LDAP disabled])
       AC_DEFINE(CURL_DISABLE_LDAP, 1, [to disable LDAP])
       AC_SUBST(CURL_DISABLE_LDAP, [1])
@@ -1366,6 +1373,9 @@ if test x$CURL_DISABLE_LDAP != x1 ; then
     CURL_CHECK_LIBS_LDAP
     case X-"$curl_cv_ldap_LIBS" in
       X-unknown)
+        if test -n "$ldap_askedfor"; then
+          AC_MSG_ERROR([couldn't detect the LDAP libraries])
+        fi
         AC_MSG_WARN([Cannot find libraries for LDAP support: LDAP disabled])
         AC_DEFINE(CURL_DISABLE_LDAP, 1, [to disable LDAP])
         AC_SUBST(CURL_DISABLE_LDAP, [1])