diff --git a/lib/isc/print.c b/lib/isc/print.c
index e5422f75dc..6271aa7b75 100644
--- a/lib/isc/print.c
+++ b/lib/isc/print.c
@@ -91,7 +91,7 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 		dot = neg = space = plus = left = zero = alt = h = l = q = 0;
 		width = precision = 0;
 		head = "";
-		length = pad = zeropad;
+		length = pad = zeropad = 0;
 
 		do {
 			if (*format == '#') {