diff --git a/src/base/string_list.hpp b/src/base/string_list.hpp
index bed3b71..7ef6595 100644
--- a/src/base/string_list.hpp
+++ b/src/base/string_list.hpp
@@ -192,7 +192,7 @@ private:
       } else if (c == '\\') {
         escaped_arg += "\\\\";
       } else {
-        if (c == ' ' || c == '&' || c == ';' || c == '>' || c == '<') {
+        if (c == ' ' || c == '&' || c == ';' || c == '>' || c == '<' || c == '|') {
           needs_quotes = true;
         }
         escaped_arg += c;