diff --git a/src/include/cpu/x86/pae.h b/src/include/cpu/x86/pae.h
index 51e47e1e85..7627187a52 100644
--- a/src/include/cpu/x86/pae.h
+++ b/src/include/cpu/x86/pae.h
@@ -2,6 +2,7 @@
 #define CPU_X86_PAE_H
 
 #include <stdint.h>
+#include <stddef.h>
 
 /* Enable paging with cr3 value for page directory pointer table as well as PAE
    option in cr4. */