diff --git a/configure.ac b/configure.ac
index 748b8ce..6924e10 100644
--- a/configure.ac
+++ b/configure.ac
@@ -41,6 +41,8 @@ case $host_os in
         ;;
 esac
 
+AC_CHECK_HEADERS([stdint.h])
+
 # Checks for pkg-config packages
 PKG_CHECK_MODULES(XFS, libfs xfont xtrans)
 XFS_CFLAGS="$XFS_CFLAGS $OS_CFLAGS"
diff --git a/difs/fontinfo.c b/difs/fontinfo.c
index 23893e0..f10b705 100644
--- a/difs/fontinfo.c
+++ b/difs/fontinfo.c
@@ -62,6 +62,21 @@ in this Software without prior written authorization from The Open Group.
 #include	<swapreq.h>
 #include	<swaprep.h>
 
+#ifdef HAVE_CONFIG_H
+#include	<config.h>
+#endif
+#ifdef HAVE_STDINT_H
+#include	<stdint.h>
+#endif
+#include	<limits.h>
+#ifndef SIZE_MAX
+# ifdef ULONG_MAX
+#  define SIZE_MAX ULONG_MAX
+# else
+#  define SIZE_MAX UINT_MAX
+# endif
+#endif
+
 void
 CopyCharInfo(
     CharInfoPtr ci,
@@ -181,6 +196,8 @@ build_range(
 	    return new;
 	}
 
+	if (src_num >= SIZE_MAX / sizeof(fsRange) * 2 - 1) 
+		return NULL;
 	np = new = (fsRange *) fsalloc(sizeof(fsRange) * (src_num + 1) / 2);
 	if (!np)
 	    return np;