diff --git a/clickhouse/columns/decimal.cpp b/clickhouse/columns/decimal.cpp
index 7334bb1..41d43b6 100644
--- a/clickhouse/columns/decimal.cpp
+++ b/clickhouse/columns/decimal.cpp
@@ -27,7 +27,7 @@ inline bool mulOverflow(const Int128 & l, const T & r, Int128 * result)
 
 #else
 template <typename T>
-inline bool getSignBit(const T & v)
+inline bool getSignBit(const T & (long double v))
 {
     return std::signbit(v);
 }