diff --git a/internal_defs.h b/internal_defs.h
index c9ffad1..621fc9c 100644
--- a/internal_defs.h
+++ b/internal_defs.h
@@ -78,16 +78,16 @@
 
 namespace scudo {
 
-typedef unsigned long uptr;
-typedef unsigned char u8;
-typedef unsigned short u16;
-typedef unsigned int u32;
-typedef unsigned long long u64;
-typedef signed long sptr;
-typedef signed char s8;
-typedef signed short s16;
-typedef signed int s32;
-typedef signed long long s64;
+typedef uintptr_t uptr;
+typedef uint8_t u8;
+typedef uint16_t u16;
+typedef uint32_t u32;
+typedef uint64_t u64;
+typedef intptr_t sptr;
+typedef int8_t s8;
+typedef int16_t s16;
+typedef int32_t s32;
+typedef int64_t s64;
 
 // The following two functions have platform specific implementations.
 void outputRaw(const char *Buffer);