diff --git a/src/of_str.cpp b/src/of_str.cpp
index b35632f..8a8f0ea 100644
--- a/src/of_str.cpp
+++ b/src/of_str.cpp
@@ -34,7 +34,7 @@ std::vector<ofString> COfStr::split(const ofString& input, const ofString& delim
 ofString COfStr::trim(const ofString& input)
 {
     size_t start = input.find_first_not_of(ofT(" \t\n\r\f\v"));
-    if (start == std::string::npos) {
+    if (start == ofString::npos) {
         return ofT("");
     }
     size_t end = input.find_last_not_of(ofT(" \t\n\r\f\v"));