diff --git a/configure b/configure
index 864c2373..5b84762c 100755
--- a/configure
+++ b/configure
@@ -19563,6 +19563,13 @@ then :
 
 fi
 
+ac_fn_cxx_check_header_compile "$LINENO" "stdint.h" "ac_cv_header_stdint_h" "$ac_includes_default"
+if test "x$ac_cv_header_stdint_h" = xyes
+then :
+  printf "%s\n" "#define HAVE_STDINT_H 1" >>confdefs.h
+
+fi
+
 
 ############################################################################
 #                 Data type and math function definitions                  #
diff --git a/configure.ac b/configure.ac
index f35c2294..a5804ec4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -52,6 +52,7 @@ AC_COIN_DEBUGLEVEL
 AC_CHECK_HEADERS([windows.h])
 AC_CHECK_HEADERS([endian.h])
 AC_CHECK_HEADERS([execinfo.h])
+AC_CHECK_HEADERS([stdint.h])
 
 ############################################################################
 #                 Data type and math function definitions                  #
diff --git a/src/CoinRational.cpp b/src/CoinRational.cpp
index 70ff289a..ddf8a956 100644
--- a/src/CoinRational.cpp
+++ b/src/CoinRational.cpp
@@ -2,6 +2,8 @@
 // Copyright 2015, Matthew Saltzman and Ted Ralphs
 // Licensed under the Eclipse Public License 
 
+#include "CoinUtilsConfig.h"
+
 #include <algorithm>
 #include <cmath>
 #ifdef __clang__
@@ -10,6 +12,9 @@
 #include <cstdio>
 #endif
 #include <cassert>
+#ifdef COINUTILS_HAS_STDINT_H
+#include <stdint.h>
+#endif
 
 #include "CoinRational.hpp"
 
@@ -20,7 +25,7 @@
 // Returns closest (or almost, anyway) rational to val with denominator less
 // than or equal to maxdnom.  Return value is true if within tolerance, false
 // otherwise.
-bool CoinRational::nearestRational_(double val, double maxdelta, long maxdnom)
+bool CoinRational::nearestRational_(double val, double maxdelta, int64_t maxdnom)
 {
   double intpart;
   if (floor(val)==val) {
@@ -31,7 +36,7 @@ bool CoinRational::nearestRational_(double val, double maxdelta, long maxdnom)
   double fracpart = fabs(modf(val, &intpart));
   // Consider using remainder() instead?
 
-  long a = 0, b = 1, c = 1, d = 1;
+  int64_t a = 0, b = 1, c = 1, d = 1;
 #define DEBUG_X 1
 #if DEBUG_X
   bool shouldBeOK = false;
@@ -83,7 +88,7 @@ bool CoinRational::nearestRational_(double val, double maxdelta, long maxdnom)
     numerator_ *= -1;
 #if DEBUG_X > 1
   if (shouldBeOK) {
-    printf("val %g is %ld/%ld to accuracy %g\n", val, numerator_, denominator_,
+    printf("val %g is %lld/%lld to accuracy %g\n", val, numerator_, denominator_,
       fabs(val - numerator_ / double(denominator_)));
   }
 #endif
diff --git a/src/CoinRational.hpp b/src/CoinRational.hpp
index 35d92f3c..e73d5e9a 100644
--- a/src/CoinRational.hpp
+++ b/src/CoinRational.hpp
@@ -14,18 +14,18 @@ class COINUTILSLIB_EXPORT CoinRational
 {
 
 public:
-  long getDenominator() { return denominator_; }
-  long getNumerator() { return numerator_; }
+  int64_t getDenominator() { return denominator_; }
+  int64_t getNumerator() { return numerator_; }
 
   CoinRational()
     : numerator_(0)
     , denominator_(1) {};
 
-  CoinRational(long n, long d)
+  CoinRational(int64_t n, int64_t d)
     : numerator_(n)
     , denominator_(d) {};
 
-  CoinRational(double val, double maxdelta, long maxdnom)
+  CoinRational(double val, double maxdelta, int64_t maxdnom)
   {
     if (!nearestRational_(val, maxdelta, maxdnom)) {
       numerator_ = 0;
@@ -34,10 +34,10 @@ class COINUTILSLIB_EXPORT CoinRational
   };
 
 private:
-  long numerator_;
-  long denominator_;
+  int64_t numerator_;
+  int64_t denominator_;
 
-  bool nearestRational_(double val, double maxdelta, long maxdnom);
+  bool nearestRational_(double val, double maxdelta, int64_t maxdnom);
 };
 
 #endif