diff --git a/include/evalhyd/detail/masks.hpp b/include/evalhyd/detail/masks.hpp
index 8a2fa4da4df28d7947806866fdddec56076655d9..a0706c557561c377a7c80aa0e6fc4feda1a72ca9 100644
--- a/include/evalhyd/detail/masks.hpp
+++ b/include/evalhyd/detail/masks.hpp
@@ -123,12 +123,12 @@ namespace evalhyd
                         const std::smatch & m = *j;
 
                         // check whether it is a range of indices, or an index
-                        if (m[0].str().find(":") != std::string::npos)
+                        if (m[0].str().find(':') != std::string::npos)
                         {
                             // it is a range of indices (i.e. t{#:#})
                             std::string s_ = m[0].str();
-                            std::string beg = s_.substr(0, s_.find(":"));
-                            std::string end = s_.substr(s_.find(":") + 1);
+                            std::string beg = s_.substr(0, s_.find(':'));
+                            std::string end = s_.substr(s_.find(':') + 1);
 
                             // generate sequence of integer indices from range
                             std::vector<int> vi(std::stoi(end) - std::stoi(beg));