diff --git a/stb_sprintf.h b/stb_sprintf.h
index ca432a6..fb49e4d 100644
--- a/stb_sprintf.h
+++ b/stb_sprintf.h
@@ -230,7 +230,7 @@ STBSP__PUBLICDEC void STB_SPRINTF_DECORATE(set_separators)(char comma, char peri
 #define stbsp__uint16 unsigned short
 
 #ifndef stbsp__uintptr
-#if defined(__ppc64__) || defined(__powerpc64__) || defined(__aarch64__) || defined(_M_X64) || defined(__x86_64__) || defined(__x86_64) || defined(__s390x__)
+#if defined(__ppc64__) || defined(__powerpc64__) || defined(__aarch64__) || defined(_M_X64) || defined(__x86_64__) || defined(__x86_64) || defined(__s390x__) || defined(__LP64__) || (defined(__riscv) && __riscv_xlen == 64)
 #define stbsp__uintptr stbsp__uint64
 #else
 #define stbsp__uintptr stbsp__uint32