diff --git a/repos/os/src/server/nic_router/bit_allocator_dynamic.h b/repos/os/src/server/nic_router/bit_allocator_dynamic.h
index e0a49a1e67..c1db6d55ce 100644
--- a/repos/os/src/server/nic_router/bit_allocator_dynamic.h
+++ b/repos/os/src/server/nic_router/bit_allocator_dynamic.h
@@ -179,6 +179,7 @@ class Genode::Bit_allocator_dynamic
 	public:
 
 		struct Out_of_indices : Exception { };
+		struct Range_conflict : Exception { };
 
 		addr_t alloc(size_t const num_log2 = 0)
 		{
@@ -206,6 +207,17 @@ class Genode::Bit_allocator_dynamic
 			throw Out_of_indices();
 		}
 
+		void alloc_addr(addr_t const bit_start, size_t const num_log2 = 0)
+		{
+			addr_t const step = 1UL << num_log2;
+			if (_array.get(bit_start, step))
+				throw Range_conflict();
+
+			_array.set(bit_start, step);
+			_next = bit_start + step;
+			return;
+		}
+
 		void free(addr_t const bit_start, size_t const num_log2 = 0)
 		{
 			_array.clear(bit_start, 1UL << num_log2);