--- a/tools/profiler/core/GeckoSampler.h
+++ b/tools/profiler/core/GeckoSampler.h
@@ -27,18 +27,19 @@ typedef mozilla::Vector<std::string> Fea
 
 static bool
 threadSelected(ThreadInfo* aInfo, const ThreadNameFilterList &aThreadNameFilters) {
   if (aThreadNameFilters.empty()) {
     return true;
   }
 
   for (uint32_t i = 0; i < aThreadNameFilters.length(); ++i) {
-    if (aThreadNameFilters[i] == aInfo->Name()) {
-      return true;
+    if (strncmp(aThreadNameFilters[i].c_str(), aInfo->Name(),
+                aThreadNameFilters[i].size()) == 0) {
+      return false;
     }
   }
 
   return false;
 }
 
 extern mozilla::TimeStamp sLastTracerEvent;
 extern int sFrameNumber;