diff --git a/configure.in b/configure.in
index 309aa03..165cecb 100644
--- a/configure.in
+++ b/configure.in
@@ -18,7 +18,7 @@
 
 dnl checks for header files
 AC_HEADER_STDC
-AC_CHECK_HEADERS(execinfo.h sys/select.h)
+AC_CHECK_HEADERS(execinfo.h sys/select.h syslog.h ctype.h)
 
 # The following test is taken from WebKit's webkit.m4
 saved_CFLAGS="$CFLAGS"