diff --git a/configure.in b/configure.in
index 44536cb05..04c70c207 100644
--- a/configure.in
+++ b/configure.in
@@ -11,6 +11,7 @@ AC_CONFIG_HEADER(tgt-vhdl/vhdl_config.h)
 AC_CANONICAL_HOST
 dnl Checks for programs.
 AC_PROG_CC
+AC_PROG_CC_C99
 AC_PROG_CXX
 AC_PROG_RANLIB
 AC_CHECK_TOOL(STRIP, strip, true)
@@ -156,7 +157,15 @@ AC_SUBST(file64_support)
 
 # Check that these functions exist. They are mostly C99
 # functions that older compilers may not yet support.
-AC_CHECK_FUNCS(lround nan fmin fmax fopen64)
+AC_CHECK_FUNCS(fopen64)
+# The following math functions may be defined in the math library so look
+# in the default libraries first and then look in -lm for them. On some
+# systems we may need to use the compiler in C99 mode to get a definition.
+# We requested C99 mode earlier with AC_PROG_CC_C99.
+AC_SEARCH_LIBS([lround], [m], [AC_DEFINE([HAVE_LROUND], [1])])
+AC_SEARCH_LIBS([nan], [m], [AC_DEFINE([HAVE_NAN], [1])])
+AC_SEARCH_LIBS([fmin], [m], [AC_DEFINE([HAVE_FMIN], [1])])
+AC_SEARCH_LIBS([fmax], [m], [AC_DEFINE([HAVE_FMAX], [1])])
 
 # Linker option used when compiling the target
 AX_LD_RDYNAMIC
diff --git a/iverilog-vpi.sh b/iverilog-vpi.sh
index 29c9a880c..d2cdfb440 100644
--- a/iverilog-vpi.sh
+++ b/iverilog-vpi.sh
@@ -19,7 +19,7 @@
 #
 
 # These are the variables used for compiling files
-CC=@IVCC@
+CC="@IVCC@"
 CXX=@IVCXX@
 CFLAGS="@PIC@ @IVCFLAGS@ -I@INCLUDEDIR@"
 
diff --git a/vvp/draw_tt.c b/vvp/draw_tt.c
index 85e3b6237..1a0491652 100644
--- a/vvp/draw_tt.c
+++ b/vvp/draw_tt.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001-2008 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2001-2009 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -117,7 +117,7 @@ static void draw_oct_table()
       printf("};\n");
 }
 
-main()
+int main()
 {
       draw_hex_table();
       draw_oct_table();