diff --git a/Problem Sets/Problem Set 1/utils.h b/Problem Sets/Problem Set 1/utils.h
index 35f954cb..7485a3da 100755
--- a/Problem Sets/Problem Set 1/utils.h	
+++ b/Problem Sets/Problem Set 1/utils.h	
@@ -8,6 +8,7 @@
 #include <cuda_runtime_api.h>
 #include <cassert>
 #include <cmath>
+#include <algorithm>
 
 #define checkCudaErrors(val) check( (val), #val, __FILE__, __LINE__)