diff --git a/uart.hpp b/uart.hpp
index 68c2d8b..e5adff3 100644
--- a/uart.hpp
+++ b/uart.hpp
@@ -123,9 +123,6 @@ class Uart {
 		constexpr char alphaChar = (LowerCase) ? 'a' : 'A';
 		constexpr size_t numDigits = detail::maxNumDigits<T, Base>();
 
-		data_t buffer[numDigits];
-		data_t *bufEnd = buffer + numDigits - 1;
-
 		T digits = val;
 
 		if (digits < 0) {
@@ -133,6 +130,9 @@ class Uart {
 			txByte('-');
 		}
 
+		data_t buffer[numDigits];
+		data_t *bufEnd = buffer + numDigits - 1;
+
 		do {
 			data_t lastDigit = digits % Base;
 			*bufEnd-- = (lastDigit < 10) ? ('0' + lastDigit) : (alphaChar + lastDigit - 10);