diff --git a/vvp/config.h.in b/vvp/config.h.in
index 55ae75887..b0dedfa82 100644
--- a/vvp/config.h.in
+++ b/vvp/config.h.in
@@ -19,7 +19,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: config.h.in,v 1.21 2006/04/25 22:41:10 steve Exp $"
+#ident "$Id: config.h.in,v 1.22 2006/04/27 05:04:59 steve Exp $"
 #endif
 
 #if defined(__cplusplus)
@@ -49,6 +49,7 @@
 # undef HAVE_READLINE_READLINE_H
 # undef HAVE_READLINE_HISTORY_H
 # undef HAVE_STDINT_H
+# undef HAVE_LROUND
 
 /* Figure if I can use readline. */
 #undef USE_READLINE
@@ -89,6 +90,14 @@ typedef unsigned long vvp_time64_t;
 # undef HAVE_SYS_RESOURCE_H
 # undef LINUX
 
+#if !defined(HAVE_LROUND)
+#if defined(__cplusplus)
+extern "C" long lround(double x);
+#else
+extern long lround(double x);
+#endif
+#endif
+
 
 /*
  * When doing dynamic linking, we need a uniform way to identify the
@@ -110,6 +119,9 @@ typedef unsigned long vvp_time64_t;
 
 /*
  * $Log: config.h.in,v $
+ * Revision 1.22  2006/04/27 05:04:59  steve
+ *  Detect missing lround function.
+ *
  * Revision 1.21  2006/04/25 22:41:10  steve
  *  Detect the presence of stdint.h
  *
diff --git a/vvp/configure.in b/vvp/configure.in
index cf5b7e848..59dc1a217 100644
--- a/vvp/configure.in
+++ b/vvp/configure.in
@@ -73,6 +73,10 @@ case "${host}" in
 	;;
 esac
 
+# Check that these functions exist. They are mostly C99
+# functions that older compilers may not yet support.
+AC_CHECK_FUNCS(lround)
+
 # see how we can give some resource usage stats with -v
 # Linux does not provide mem stats in rusage, use /proc/self/statm.
 
diff --git a/vvp/main.cc b/vvp/main.cc
index 93540b52f..35c62af0b 100644
--- a/vvp/main.cc
+++ b/vvp/main.cc
@@ -17,7 +17,7 @@
  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  */
 #ifdef HAVE_CVS_IDENT
-#ident "$Id: main.cc,v 1.40 2005/01/29 06:28:19 steve Exp $"
+#ident "$Id: main.cc,v 1.41 2006/04/27 05:04:59 steve Exp $"
 #endif
 
 # include  "config.h"
@@ -53,6 +53,21 @@ extern "C" int optind;
 extern "C" const char*optarg;
 #endif
 
+#if !defined(HAVE_LROUND)
+/*
+ * If the system doesn't provide the lround function, then we provide
+ * it ourselves here. It is simply the nearest integer, rounded away
+ * from zero.
+ */
+extern "C" long int lround(float x)
+{
+      if (x >= 0.0)
+	    return floor(x+0.5);
+      else
+	    return ceil(x-0.5);
+}
+#endif
+
 bool verbose_flag = false;
 
 static char log_buffer[4096];
@@ -281,6 +296,9 @@ int main(int argc, char*argv[])
 
 /*
  * $Log: main.cc,v $
+ * Revision 1.41  2006/04/27 05:04:59  steve
+ *  Detect missing lround function.
+ *
  * Revision 1.40  2005/01/29 06:28:19  steve
  *  Add the -s flag to start up interactive.
  *