--- a/Integer.h
+++ b/Integer.h
@@ -23,6 +23,7 @@
 #include <gmp_init.h>
 #include <cctype>
 #include <limits>
+#include <climits>
 
 class Integer; class Rational;
 
--- a/Rational.cc
+++ b/Rational.cc
@@ -17,6 +17,7 @@
 
 #include <cctype>
 #include "Rational.h"
+#include <cstring>
 
 Rational& Rational::set(const char* s) throw (gmp_error)
 {
--- a/Rational.h
+++ b/Rational.h
@@ -17,6 +17,7 @@
 #define _POLYMAKE_GMP_RATIONAL_H "$Project: polymake $$Id$
 
 #include <Integer.h>
+#include <cstring>
 
 #if __GNU_MP_VERSION < 4
 #define _tmp_little_Integer(x) \
@@ -1178,7 +1179,7 @@ std::basic_ostream<char, Traits>& operat
    Integer::little_buffer buf(s);
    numerator(a).putstr(os.flags(), buf);
    if (show_den) {
-      char *den_buf=buf+strlen(buf);
+      char *den_buf=buf+std::strlen(buf);
       *den_buf++ = '/';
       denominator(a).putstr(os.flags(), den_buf);
    }
--- a/gmp_init.cc
+++ b/gmp_init.cc
@@ -16,6 +16,7 @@
 #ident "$Project: polymake $$Id$
 
 #include <memory>
+#include <cstring>
 #include "gmp_init.h"
 
 #if defined(__GNUC__)