diff --git a/lib/RevBank/Amount.pm b/lib/RevBank/Amount.pm
index 2fd8f3a..98c97df 100644
--- a/lib/RevBank/Amount.pm
+++ b/lib/RevBank/Amount.pm
@@ -118,7 +118,7 @@ sub string_flipped($self, $sep = " ") {
     return sprintf(
         "%s%s%d.%02d",
         $$self > 0 ? "+" : "",
-        $sep,
+        $$self > 0 ? $sep : "",
         abs($$self) / 100,
         abs($$self) % 100,
     );