diff --git a/src/xrpld/app/wasm/detail/HostFuncImplFloat.cpp b/src/xrpld/app/wasm/detail/HostFuncImplFloat.cpp
index 36231ec37d..abff96a08d 100644
--- a/src/xrpld/app/wasm/detail/HostFuncImplFloat.cpp
+++ b/src/xrpld/app/wasm/detail/HostFuncImplFloat.cpp
@@ -93,7 +93,7 @@ public:
     makeNumber(int64_t mantissa, int32_t exponent)
     {
         if (mantissa < 0)
-            return Number(true, -mantissa, exponent, Number::normalized());
+            return Number(true, -static_cast<uint64_t>(mantissa), exponent, Number::normalized());
         return Number(false, mantissa, exponent, Number::normalized());
     }