diff --git a/src/converters/converter.cpp b/src/converters/converter.cpp
index 9525e11..b49e009 100644
--- a/src/converters/converter.cpp
+++ b/src/converters/converter.cpp
@@ -34,7 +34,7 @@ CONVERTER_PRIMITIVE_ST(float, std::stof(std::string{str}));
 CONVERTER_PRIMITIVE_ST(double, std::stod(std::string{str}));
 CONVERTER_PRIMITIVE_ST(long_double, std::stold(std::string{str}));
 
-#if UINTPTR_WIDTH >= 64
+#if __x86_64__
 CONVERTER_PRIMITIVE_ST(long_long_unsigned_int_t, std::stoull(std::string{str}));
 #endif
 
diff --git a/src/converters/converter.h b/src/converters/converter.h
index 102dca5..761ed4c 100644
--- a/src/converters/converter.h
+++ b/src/converters/converter.h
@@ -52,7 +52,7 @@ namespace ts {
 
     CONVERTER_PRIMITIVE(int64_t);
     CONVERTER_PRIMITIVE(uint64_t);
-#if UINTPTR_WIDTH >= 64
+#if __x86_64__
     CONVERTER_PRIMITIVE(long_long_unsigned_int_t);
 #endif
     typedef std::string std__string;