diff --git a/spot/ltsmin/ltsmin.cc b/spot/ltsmin/ltsmin.cc
index c893793b7..d984650e8 100644
--- a/spot/ltsmin/ltsmin.cc
+++ b/spot/ltsmin/ltsmin.cc
@@ -234,6 +234,7 @@ namespace spot
       fixed_size_pool* p = static_cast<fixed_size_pool*>(ctx->pool);
       spins_state* out =
         new(p->allocate()) spins_state(ctx->state_size, p);
+      assert(out != nullptr);
       memcpy(out->vars, dst, ctx->state_size * sizeof(int));
       out->compute_hash();
       ctx->transitions.emplace_back(out);
@@ -251,6 +252,7 @@ namespace spot
                               - sizeof(spins_compressed_state::vars)
                               + sizeof(int) * csize);
       spins_compressed_state* out = new(mem) spins_compressed_state(csize, p);
+      assert(out != nullptr);
       memcpy(out->vars, ctx->compressed, csize * sizeof(int));
       out->compute_hash();
       ctx->transitions.emplace_back(out);
@@ -711,6 +713,7 @@ namespace spot
                                     + sizeof(int) * csize);
             spins_compressed_state* res = new(mem)
               spins_compressed_state(csize, p);
+            assert(res != nullptr);
             memcpy(res->vars, compressed_, csize * sizeof(int));
             res->compute_hash();
             return res;
@@ -719,6 +722,7 @@ namespace spot
           {
             fixed_size_pool* p = const_cast<fixed_size_pool*>(&statepool_);
             spins_state* res = new(p->allocate()) spins_state(state_size_, p);
+            assert(res != nullptr);
             d_->get_initial_state(res->vars);
             res->compute_hash();
             return res;
diff --git a/spot/twaalgos/langmap.cc b/spot/twaalgos/langmap.cc
index 3ba6b3b23..a3a77715d 100644
--- a/spot/twaalgos/langmap.cc
+++ b/spot/twaalgos/langmap.cc
@@ -45,6 +45,7 @@ namespace spot
     for (unsigned i = 0; i < n_states; ++i)
       {
         twa_graph_ptr c = make_twa_graph(aut, twa::prop_set::all());
+        assert(c); // for some reason g++ 7.3 thinks this could be null
         c->set_init_state(i);
         alt_init_st_auts[i] = c;
         compl_alt_init_st_auts[i] = remove_fin(dualize(c));
diff --git a/spot/twaalgos/tau03opt.cc b/spot/twaalgos/tau03opt.cc
index 494145afe..038ebabe4 100644
--- a/spot/twaalgos/tau03opt.cc
+++ b/spot/twaalgos/tau03opt.cc
@@ -408,7 +408,7 @@ namespace spot
       public:
         color_ref(hash_type* h, hcyan_type* hc, const state* s,
                   const weight* w, acc_cond::mark_t* a)
-          : is_cyan(true), w(w), ph(h), phc(hc), ps(s), acc(a)
+          : is_cyan(true), w(w), ph(h), phc(hc), ps(s), pc(nullptr), acc(a)
           {
           }
         color_ref(color* c, acc_cond::mark_t* a)