diff --git a/Eigen/Core b/Eigen/Core
index 1a3249604..80842a1de 100644
--- a/Eigen/Core
+++ b/Eigen/Core
@@ -61,6 +61,7 @@
   #pragma GCC optimize ("-fno-ipa-cp-clone")
 #endif
 
+#include <stdint.h>
 #include <complex>
 
 // this include file manages BLAS and MKL related macros