diff --git a/src/vsnprintf.c b/src/vsnprintf.c
new file mode 100644
index 000000000..94485c5f5
--- /dev/null
+++ b/src/vsnprintf.c
@@ -0,0 +1,127 @@
+/*
+ * "$Id: vsnprintf.c,v 1.1 1998/11/05 16:07:45 mike Exp $"
+ *
+ * vsnprintf() function for the Fast Light Tool Kit (FLTK).
+ *
+ * Emulates this call on systems that lack it (pretty much everything
+ * except glibc systems).
+ *
+ * KNOWN BUGS:
+ *
+ * Field width & Precision is ignored for %%, %c, and %s.
+ *
+ * A malicious user who manages to create a %-fmt string that prints
+ * more than 99 characters can still overflow the temporary buffer.
+ * For instance %110f will overflow.
+ *
+ * Only handles formats that are both documented in the glibc man page
+ * for printf and also handled by your system's sprintf().
+ *
+ * Copyright 1998 by Bill Spitzak and others.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+ * USA.
+ *
+ * Please report all bugs and problems to "fltk-bugs@easysw.com".
+ */
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <config.h>
+
+#if !HAVE_VSNPRINTF
+
+int vsnprintf(char* str, size_t size, const char* fmt, va_list ap) {
+  const char* e = str+size-1;
+  char* p = str;
+  char copy[20];
+  char* copy_p;
+  char sprintf_out[100];
+
+  while (*fmt && p < e) {
+    if (*fmt != '%') {
+      *p++ = *fmt++;
+    } else {
+      fmt++;
+      copy[0] = '%';
+      for (copy_p = copy+1; copy_p < copy+19;) {
+	switch ((*copy_p++ = *fmt++)) {
+	case 0:
+	  fmt--; goto CONTINUE;
+	case '%':
+	  *p++ = '%'; goto CONTINUE;
+	case 'c':
+	  *p++ = va_arg(ap, int);
+	  goto CONTINUE;
+	case 'd':
+	case 'i':
+	case 'o':
+	case 'u':
+	case 'x':
+	case 'X':
+	  *copy_p = 0;
+	  sprintf(sprintf_out, copy, va_arg(ap, int));
+	  copy_p = sprintf_out;
+	  goto DUP;
+	case 'e':
+	case 'E':
+	case 'f':
+	case 'g':
+	  *copy_p = 0;
+	  sprintf(sprintf_out, copy, va_arg(ap, double));
+	  copy_p = sprintf_out;
+	  goto DUP;
+	case 'p':
+	  *copy_p = 0;
+	  sprintf(sprintf_out, copy, va_arg(ap, void*));
+	  copy_p = sprintf_out;
+	  goto DUP;
+	case 'n':
+	  *(va_arg(ap, int*)) = p-str;
+	  goto CONTINUE;
+	case 's':
+	  copy_p = va_arg(ap, char*);
+	  if (!copy_p) copy_p = "NULL";
+	DUP:
+	  while (*copy_p && p < e) *p++ = *copy_p++;
+	  goto CONTINUE;
+	}
+      }
+    }
+  CONTINUE:;
+  }
+  *p = 0;
+  if (*fmt) return -1;
+  return p-str;
+}
+
+#endif
+
+#if !HAVE_SNPRINTF
+
+int snprintf(char* str, size_t size, const char* fmt, ...) {
+  int ret;
+  va_list ap;
+  va_start(ap, fmt);
+  ret = vsnprintf(str, size, fmt, ap);
+  va_end(ap);
+  return ret;
+}
+
+#endif
+
+/*
+ * End of "$Id: vsnprintf.c,v 1.1 1998/11/05 16:07:45 mike Exp $".
+ */