diff --git a/src/atlas/grid/Partitioner.h b/src/atlas/grid/Partitioner.h
index aa43826b1..67b9333f8 100644
--- a/src/atlas/grid/Partitioner.h
+++ b/src/atlas/grid/Partitioner.h
@@ -76,7 +76,7 @@ class Partitioner : DOXYGEN_HIDE(public util::ObjectHandle<detail::partitioner::
 public:
     using Handle::Handle;
     Partitioner() = default;
-    Partitioner(const std::string& type);
+    explicit Partitioner(const std::string& type);
     Partitioner(const std::string& type, const idx_t nb_partitions);
     Partitioner(const Config&);
     Partitioner(const std::string& type, const Config&);