diff --git a/src/modp_numtoa.c b/src/modp_numtoa.c
index e7b074d876..ab6b2c95e8 100644
--- a/src/modp_numtoa.c
+++ b/src/modp_numtoa.c
@@ -57,7 +57,7 @@ void modp_uitoa10(uint32_t value, char* str)
 void modp_litoa10(int64_t value, char* str)
 {
     char* wstr=str;
-    uint64_t uvalue = (value < 0) ? -value : value;
+    uint64_t uvalue = (value < 0) ? (value == INT64_MIN ? (uint64_t)(INT64_MAX) + 1 : -value) : value;
 
     // Conversion. Number is reversed.
     do *wstr++ = (char)(48 + (uvalue % 10)); while(uvalue /= 10);