diff --git a/Barbershop-problem.pro b/Barbershop-problem.pro
index 595bdaa..c788f24 100644
--- a/Barbershop-problem.pro
+++ b/Barbershop-problem.pro
@@ -5,3 +5,5 @@ CONFIG -= qt
 
 SOURCES += \
         main.cpp
+
+LIBS += pthread