diff --git a/util.cpp b/util.cpp
index bc6af153..73a16e55 100644
--- a/util.cpp
+++ b/util.cpp
@@ -381,6 +381,7 @@ cld exp_parser::parse(int prio) {
     else if(number == "i") res = cld(0, 1);
     else if(number == "inf") res = HUGE_VAL;
     else if(number == "p" || number == "pi") res = M_PI;
+    else if(number == "tau") res = TAU;
     else if(number == "" && next() == '-') { at++; res = -parse(20); }
     else if(number == "") throw hr_parse_exception("number missing, " + where());
     else if(number == "s") res = ticks / 1000.;