diff --git a/configure.ac b/configure.ac
index 10892754a..a7e4d2d57 100644
--- a/configure.ac
+++ b/configure.ac
@@ -458,11 +458,15 @@ AC_HEADER_TIME
 AC_STRUCT_TM
 
 dnl Checks for library functions.
+old_LIBS=$LIBS
+LIBS="$base_LIBS $network_LIBS $opengl_LIBS"
 AC_TYPE_SIGNAL
 AC_FUNC_VPRINTF
-AC_CHECK_FUNCS( \
+AC_CHECK_FUNCS( [ \
         ftime gettimeofday timegm memcpy bcopy mktime strstr rand mkfifo \
-	random drand48 setitimer getitimer signal GetLocalTime rint getrusage )
+	random drand48 setitimer getitimer signal GetLocalTime rint getrusage \
+	truncf ] )
+LIBS=$old_LIBS
 
 AM_CONFIG_HEADER(src/Include/config.h)
 
diff --git a/src/Cockpit/panel.cxx b/src/Cockpit/panel.cxx
index 53a9bde58..16d7b7792 100644
--- a/src/Cockpit/panel.cxx
+++ b/src/Cockpit/panel.cxx
@@ -53,7 +53,7 @@
 // my hardware/driver requires many more.
 #define POFF_UNITS 4
 
-#if defined( __FreeBSD__ ) || defined( _MSC_VER )	// no truncf on FreeBSD nor in MSVC
+#ifndef HAVE_TRUNCF
 inline float truncf (float d) {
     return (d < 0) ? -floorf(-d) : floorf(d);
 }