diff --git a/include/evalhyd/evalp.hpp b/include/evalhyd/evalp.hpp
index ce9d8e02f2ad737d536c33171d904ab0bfeea100..3263d26388fa9504254fc61d0a7cee868a8c500c 100644
--- a/include/evalhyd/evalp.hpp
+++ b/include/evalhyd/evalp.hpp
@@ -100,7 +100,7 @@ namespace evalhyd
         );
 
         // check that optional parameters are given as arguments
-        eh::utils::check_optionals(metrics, q_thr);
+        eh::utils::evalp::check_optionals(metrics, q_thr);
 
         // check that data dimensions are compatible
         // > time
diff --git a/src/utils.hpp b/src/utils.hpp
index 863763939b2b57b27c83cdc9696f6917348d761e..5efbceec1640d2969caa8ce9bb6fc5dd21eadceb 100644
--- a/src/utils.hpp
+++ b/src/utils.hpp
@@ -92,30 +92,33 @@ namespace evalhyd
             }
         }
 
-        /// Procedure to check that optional parameters are provided
-        /// as arguments when required metrics need them.
-        ///
-        /// \param [in] metrics:
-        ///     Vector of strings for the metric(s) to be computed.
-        /// \param [in] thresholds:
-        ///     Array of thresholds for metrics based on exceedance events.
-        inline void check_optionals (
-                const std::vector<std::string>& metrics,
-                const xt::xtensor<double, 1>& thresholds
-        )
+        namespace evalp
         {
-            std::vector<std::string>threshold_metrics =
-                    {"BS", "BS_CRD", "BS_LBD", "BSS"};
-
-            for (const auto& metric : metrics)
+            /// Procedure to check that optional parameters are provided
+            /// as arguments when required metrics need them.
+            ///
+            /// \param [in] metrics:
+            ///     Vector of strings for the metric(s) to be computed.
+            /// \param [in] thresholds:
+            ///     Array of thresholds for metrics based on exceedance events.
+            inline void check_optionals (
+                    const std::vector<std::string>& metrics,
+                    const xt::xtensor<double, 1>& thresholds
+            )
             {
-                if (std::find(threshold_metrics.begin(), threshold_metrics.end(),
-                              metric) != threshold_metrics.end())
-                    if (thresholds.size() < 1)
-                        throw std::runtime_error(
-                                "missing thresholds *q_thr* required to "
-                                "compute " + metric
-                        );
+                std::vector<std::string>threshold_metrics =
+                        {"BS", "BS_CRD", "BS_LBD", "BSS"};
+
+                for (const auto& metric : metrics)
+                {
+                    if (std::find(threshold_metrics.begin(), threshold_metrics.end(),
+                                  metric) != threshold_metrics.end())
+                        if (thresholds.size() < 1)
+                            throw std::runtime_error(
+                                    "missing thresholds *q_thr* required to "
+                                    "compute " + metric
+                            );
+                }
             }
         }
     }