diff --git a/ortools/pdlp/test_util_test.cc b/ortools/pdlp/test_util_test.cc
index 555a9b2cc4..c92e164f68 100644
--- a/ortools/pdlp/test_util_test.cc
+++ b/ortools/pdlp/test_util_test.cc
@@ -13,6 +13,7 @@
 
 #include "ortools/pdlp/test_util.h"
 
+#define _USE_MATH_DEFINES  // Needed for visual studio for M_PI.
 #include <cmath>
 #include <deque>
 #include <limits>