diff --git a/lib/strtoofft.h b/lib/strtoofft.h
index c556404d55..3bea048e64 100644
--- a/lib/strtoofft.h
+++ b/lib/strtoofft.h
@@ -58,7 +58,7 @@
 #endif
 
 #define CURL_LLONG_MAX CURL_OFF_T_C(0x7FFFFFFFFFFFFFFF)
-#define CURL_LLONG_MIN CURL_OFF_T_C(0x8000000000000000)
+#define CURL_LLONG_MIN (-CURL_LLONG_MAX - CURL_OFF_T_C(1))
 
 #endif