diff --git a/internal_defs.h b/internal_defs.h
index 621fc9c..c9ffad1 100644
--- a/internal_defs.h
+++ b/internal_defs.h
@@ -78,16 +78,16 @@
 
 namespace scudo {
 
-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;
+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;
 
 // The following two functions have platform specific implementations.
 void outputRaw(const char *Buffer);