diff --git a/test.json b/test.json
index 6f0f2dbd..3a37d992 100644
--- a/test.json
+++ b/test.json
@@ -13,5 +13,6 @@
   ],
   "'NULL' U+0000": "\u0000",
   "'VULGAR FRACTION ONE HALF' U+00BD": "\u00BD",
-  "'PILE OF POO' U+1F4A9": "\uD83D\uDCA9"
+  "'PILE OF POO' U+1F4A9": "\uD83D\uDCA9",
+  "min_int": "-4611686018427387904"
 }
diff --git a/write.ml b/write.ml
index d5968ed9..6e3f51f8 100644
--- a/write.ml
+++ b/write.ml
@@ -85,7 +85,7 @@ let rec write_digits s pos x =
   else
     let d = x mod 10 in
     let pos = write_digits s pos (x / 10) in
-    s.[pos] <- dec d;
+    s.[pos] <- dec (abs d);
     pos + 1
 
 let write_int ob x =
@@ -96,7 +96,7 @@ let write_int ob x =
     let s = ob.o_s in
     let pos = ob.o_len in
     s.[pos] <- '-';
-    ob.o_len <- write_digits s (pos + 1) (abs x)
+    ob.o_len <- write_digits s (pos + 1) x
   )
   else
     Bi_outbuf.add_char ob '0'