diff --git a/cpp/core/math/constrained_least_squares.h b/cpp/core/math/constrained_least_squares.h
index 3524bc68a8..2c642e1aa9 100644
--- a/cpp/core/math/constrained_least_squares.h
+++ b/cpp/core/math/constrained_least_squares.h
@@ -237,7 +237,9 @@ template <typename ValueType> class Solver {
     lambda_prev.setZero();
     // set active set empty:
     active.setZero();
-    active.tail(num_ineq).setOnes();
+    if (num_eq > 0) {
+      active.tail(num_eq).setOnes();
+    }
 
     // initial estimate of constraint values:
     c = c_u;