diff --git a/test/unit/test_lif_cell_group.cpp b/test/unit/test_lif_cell_group.cpp
index b2241b2ff3bda7988bbbb5cdec009272affafd20..93718e9f90a6d8cb8eb871fa14b6a4a3f3f1468a 100644
--- a/test/unit/test_lif_cell_group.cpp
+++ b/test/unit/test_lif_cell_group.cpp
@@ -258,7 +258,7 @@ TEST(lif_cell_group, probe) {
     auto fun = [&ums](probe_metadata pm,
                   std::size_t n,
                   const sample_record* samples) {
-        for (int ix = 0; ix < n; ++ix) {
+        for (std::size_t ix = 0; ix < n; ++ix) {
             const auto& [t, v] = samples[ix];
             double u = *util::any_cast<double*>(v);
             ums[pm.id].push_back({t, u});
@@ -684,7 +684,7 @@ std::vector<Um_type> exp = {{ 0, -18 },
     ASSERT_FALSE(testing::seq_eq(ums[{1, 0}], exp));
     // now check the spikes
     std::sort(spikes.begin(), spikes.end());
-    EXPECT_EQ(spikes.size(), 3);
+    EXPECT_EQ(spikes.size(), 3u);
     std::vector<double> sexp{2, 4, 5};
     ASSERT_TRUE(testing::seq_almost_eq<double>(spikes, sexp));
 }
diff --git a/test/unit/test_segment_tree.cpp b/test/unit/test_segment_tree.cpp
index f7c16b6daf0a6815017fdd43bc0034724ef7a218..571f332f001353191c766704e277bd362de74590 100644
--- a/test/unit/test_segment_tree.cpp
+++ b/test/unit/test_segment_tree.cpp
@@ -353,12 +353,13 @@ TEST(segment_tree, tag_roots) {
             EXPECT_EQ((std::vector<arb::msize_t>{3}), arb::tag_roots(tree, 3));
         }
     }
-    // gnarly tree
-    // (npos) - 0 - 1 - 4
-    //            \
-    //              2 - 3
-    //                \
-    //                  5
+    /* gnarly tree
+    ** (npos) - 0 - 1 - 4
+    **            \
+    **              2 - 3
+    **                \
+    **                  5
+    */
     {
         arb::segment_tree tree;
         tree.append(arb::mnpos, {0, 0, 0}, {0, 0, 1}, 1); // 0