--- a/configure.ac
+++ b/configure.ac
@@ -482,7 +482,7 @@
   checkpthread=yes
 
   AC_MSG_CHECKING([for pthread_create with libc])
-  AC_TRY_LINK([], [pthread_create();], 
+  AC_TRY_LINK([#include <pthread.h>], [pthread_create(0,0,0,0);], 
                   [pthflag=yes; checkpthread=no], 
                   [pthflag=no])
   AC_MSG_RESULT($pthflag)
@@ -492,7 +492,7 @@
       AC_MSG_CHECKING([for pthread_create with -$flag])
       OLDLIBS="$LIBS"
       LIBS="$LIBS -$flag"
-      AC_TRY_LINK([], [pthread_create();], 
+      AC_TRY_LINK([#include <pthread.h>], [pthread_create(0,0,0,0);], 
                       [pthflag=yes; checkpthread=no], 
                       [pthflag=no; LIBS="$OLDLIBS"])
       AC_MSG_RESULT($pthflag)
@@ -626,7 +626,7 @@
   AC_CHECK_HEADER(curl/curl.h, [libcurl=yes])
   if test "x$libcurl" = "xyes"; then
       AC_MSG_CHECKING([whether with-curl compiles and links fine])
-      AC_TRY_LINK([], [curl_easy_init();], [libcurl=yes], [libcurl=no])
+      AC_TRY_LINK([#include <curl/curl.h>], [curl_easy_init();], [libcurl=yes], [libcurl=no])
       AC_MSG_RESULT([$libcurl])
   fi
    if test "x$libcurl" = "xno"; then
@@ -640,12 +640,12 @@
       AC_CHECK_HEADER(curl/curl.h, [libcurl=yes])
       if test "x$libcurl" = "xyes"; then
           AC_MSG_CHECKING([whether curl-config hints compiles and links fine])
-          OLDFLAGS="$LDFLAGS"
-          LDFLAGS="$LDFLAGS `$libcurlconfig --libs 2>/dev/null`"
-          AC_TRY_LINK([], [curl_easy_init();], [libcurl=yes], [libcurl=no])
+          OLDLIBS="$LIBS"
+          LIBS="$LIBS `$libcurlconfig --libs 2>/dev/null`"
+          AC_TRY_LINK([#include <curl/curl.h>], [curl_easy_init();], [libcurl=yes], [libcurl=no])
           AC_MSG_RESULT([$libcurl])
           if test "x$libcurl" = "xno"; then
-              LDFLAGS="$OLDFLAGS"
+              LIBS="$OLDLIBS"
           fi
       fi

@@ -684,7 +684,7 @@
   AC_CHECK_HEADER(expat.h, [libexpat=yes])
   if test "x$libexpat" = "xyes"; then
       AC_MSG_CHECKING([whether with-expat compiles and links fine])
-      AC_TRY_LINK([], [XML_SetElementHandler();], [libexpat=yes], [libexpat=no])
+      AC_TRY_LINK([#include <expat.h>], [XML_SetElementHandler(0,0,0);], [libexpat=yes], [libexpat=no])
       AC_MSG_RESULT([$libexpat])
   fi
    if test "x$libexpat" = "xno"; then
@@ -695,12 +695,12 @@
   AC_CHECK_HEADER(expat.h, [libexpat=yes])
   if test "x$libexpat" = "xyes"; then
     AC_MSG_CHECKING([whether libexpat compiles and links fine])
-    OLDFLAGS="$LDFLAGS"
-    LDFLAGS="$LDFLAGS -lexpat"
-    AC_TRY_LINK([], [XML_SetElementHandler();], [libexpat=yes], [libexpat=no])
+    OLDLIBS="$LIBS"
+    LIBS="$LIBS -lexpat"
+    AC_TRY_LINK([#include <expat.h>], [XML_SetElementHandler(0,0,0);], [libexpat=yes], [libexpat=no])
     AC_MSG_RESULT([$libexpat])
     if test "x$libexpat" = "xno"; then
-      LDFLAGS="$OLDFLAGS"
+      LIBS="$OLDLIBS"
     fi
   fi
 fi