diff --git a/CHANGELOG.md b/CHANGELOG.md
index 63abdd543..2e514ebe5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@
 
 ### Changed
 
+- A mix of empty and non-empty `skills` arrays is allowed in input (#460)
 - Formatting script updated to use version 10 of clang-format (#452)
 - vroom will now read json input from stdin if no other input is specified (#457)
 
diff --git a/docs/API.md b/docs/API.md
index a5f644754..f4e6879c8 100644
--- a/docs/API.md
+++ b/docs/API.md
@@ -186,9 +186,14 @@ served by a vehicle that has **all** its required skills. In other
 words: job `j` is eligible to vehicle `v` iff `j.skills` is included
 in `v.skills`.
 
-In order to ease modeling problems with no skills required, it is
-assumed that there is no restriction at all if no `skills` keys are
-provided.
+This definition implies in particular that:
+
+- a task without skills can be served by any vehicle;
+- a vehicle without skills can only serve tasks with no particular
+  need (i.e. without skills as well).
+
+In order to ease modeling problems with no skills required, not
+providing a `skills` key default to providing an empty array.
 
 ### Task priorities
 
diff --git a/src/structures/vroom/input/input.cpp b/src/structures/vroom/input/input.cpp
index 692231342..8ed9b9ea5 100644
--- a/src/structures/vroom/input/input.cpp
+++ b/src/structures/vroom/input/input.cpp
@@ -17,7 +17,6 @@ namespace vroom {
 
 Input::Input(unsigned amount_size)
   : _start_loading(std::chrono::high_resolution_clock::now()),
-    _no_addition_yet(true),
     _has_TW(false),
     _homogeneous_locations(true),
     _geometry(false),
@@ -56,18 +55,9 @@ void Input::check_job(Job& job) {
                       std::to_string(_amount_size) + '.');
   }
 
-  // Ensure that skills are either always or never provided.
-  if (_no_addition_yet) {
-    _has_skills = !job.skills.empty();
-    _no_addition_yet = false;
-  } else {
-    if (_has_skills != !job.skills.empty()) {
-      throw Exception(ERROR::INPUT, "Missing skills.");
-    }
-  }
-
-  // Check for time-windows.
-  _has_TW |= (!(job.tws.size() == 1) or !job.tws[0].is_default());
+  // Check for time-windows and skills.
+  _has_TW = _has_TW || (!(job.tws.size() == 1) or !job.tws[0].is_default());
+  _has_skills = _has_skills || !job.skills.empty();
 
   if (!job.location.user_index()) {
     // Index of this job in the matrix was not specified upon job
@@ -159,18 +149,9 @@ void Input::add_vehicle(const Vehicle& vehicle) {
                       std::to_string(_amount_size) + '.');
   }
 
-  // Ensure that skills are either always or never provided.
-  if (_no_addition_yet) {
-    _has_skills = !current_v.skills.empty();
-    _no_addition_yet = false;
-  } else {
-    if (_has_skills != !current_v.skills.empty()) {
-      throw Exception(ERROR::INPUT, "Missing skills.");
-    }
-  }
-
-  // Check for time-windows.
+  // Check for time-windows and skills.
   _has_TW = _has_TW || !vehicle.tw.is_default();
+  _has_skills = _has_skills || !current_v.skills.empty();
 
   bool has_start = current_v.has_start();
   bool has_end = current_v.has_end();
@@ -316,11 +297,9 @@ void Input::set_skills_compatibility() {
   if (_has_skills) {
     for (std::size_t v = 0; v < vehicles.size(); ++v) {
       const auto& v_skills = vehicles[v].skills;
-      assert(!v_skills.empty());
 
       for (std::size_t j = 0; j < jobs.size(); ++j) {
         bool is_compatible = true;
-        assert(!jobs[j].skills.empty());
         for (const auto& s : jobs[j].skills) {
           if (v_skills.find(s) == v_skills.end()) {
             is_compatible = false;
diff --git a/src/structures/vroom/input/input.h b/src/structures/vroom/input/input.h
index bca4d7e52..3f995aba7 100644
--- a/src/structures/vroom/input/input.h
+++ b/src/structures/vroom/input/input.h
@@ -31,7 +31,6 @@ class Input {
   std::chrono::high_resolution_clock::time_point _end_solving;
   std::chrono::high_resolution_clock::time_point _end_routing;
   std::unique_ptr<routing::Wrapper> _routing_wrapper;
-  bool _no_addition_yet;
   bool _has_skills;
   bool _has_TW;
   bool _homogeneous_locations;