diff --git a/src/arch/i386/include/bits/stdint.h b/src/arch/i386/include/bits/stdint.h
index 6ccf0971..9eb72e9c 100644
--- a/src/arch/i386/include/bits/stdint.h
+++ b/src/arch/i386/include/bits/stdint.h
@@ -1,8 +1,8 @@
 #ifndef _BITS_STDINT_H
 #define _BITS_STDINT_H
 
-typedef unsigned int		size_t;
-typedef signed int		ssize_t;
+typedef __SIZE_TYPE__		size_t;
+typedef signed long		ssize_t;
 typedef signed long		off_t;
 
 typedef unsigned char		uint8_t;
diff --git a/src/arch/x86_64/include/bits/stdint.h b/src/arch/x86_64/include/bits/stdint.h
index 23bae9c4..9eb72e9c 100644
--- a/src/arch/x86_64/include/bits/stdint.h
+++ b/src/arch/x86_64/include/bits/stdint.h
@@ -1,7 +1,7 @@
 #ifndef _BITS_STDINT_H
 #define _BITS_STDINT_H
 
-typedef unsigned long		size_t;
+typedef __SIZE_TYPE__		size_t;
 typedef signed long		ssize_t;
 typedef signed long		off_t;
 
diff --git a/src/include/stdint.h b/src/include/stdint.h
index 4b0e44f2..dc4bd8c7 100644
--- a/src/include/stdint.h
+++ b/src/include/stdint.h
@@ -1,6 +1,16 @@
 #ifndef _STDINT_H
 #define _STDINT_H
 
+/*
+ * This is a standard predefined macro on all gcc's I've seen. It's
+ * important that we define size_t in the same way as the compiler,
+ * because that's what it's expecting when it checks %zd/%zx printf
+ * format specifiers.
+ */
+#ifndef __SIZE_TYPE__
+#define __SIZE_TYPE__ unsigned long /* safe choice on most systems */
+#endif
+
 #include <bits/stdint.h>
 
 typedef int8_t s8;