diff --git a/include/parallelzone/hardware/ram/ram.hpp b/include/parallelzone/hardware/ram/ram.hpp
index ae48bb29..046f1689 100644
--- a/include/parallelzone/hardware/ram/ram.hpp
+++ b/include/parallelzone/hardware/ram/ram.hpp
@@ -25,7 +25,7 @@ namespace parallelzone::hardware {
 
 namespace detail_ {
 
-class RAMPIMPL;
+struct RAMPIMPL;
 }
 
 /** @brief Provides a runtime API for interacting with memory
diff --git a/include/parallelzone/mpi_helpers/commpp/commpp.ipp b/include/parallelzone/mpi_helpers/commpp/commpp.ipp
index 87ee8de9..893245aa 100644
--- a/include/parallelzone/mpi_helpers/commpp/commpp.ipp
+++ b/include/parallelzone/mpi_helpers/commpp/commpp.ipp
@@ -90,7 +90,7 @@ typename CommPP::gather_return_type<T> CommPP::gather_t_(
         auto serialized_size = buffer.size() / size();
 
         value_type vec(size());
-        for(size_type i = 0, j = 0; i < buffer.size();
+        for(size_type i = 0, j = 0; i < size_type(buffer.size());
             i += serialized_size, ++j) {
             const_binary_reference view(binary_rv->data() + i, serialized_size);
             vec[j] = std::move(from_binary_view<clean_type>(view));
@@ -122,8 +122,6 @@ typename CommPP::gather_return_type<T> CommPP::gatherv_t_(
     using return_type = typename CommPP::gather_return_type<clean_type>;
     using value_type  = typename return_type::value_type;
 
-    const bool am_i_root = root.has_value() ? me() == *root : true;
-
     if constexpr(needs_serialized_v<clean_type>) {
         //  Do gather in binary
         auto binary    = make_binary_buffer(std::forward<T>(input));
@@ -165,8 +163,7 @@ typename CommPP::gather_return_type<T> CommPP::gatherv_t_(
         constexpr auto t_size = sizeof(element_type);
 
         value_type vec;
-        auto n_elements = buffer.size() / t_size;
-        for(size_type i = 0; i < buffer.size(); i += t_size) {
+        for(size_type i = 0; i < size_type(buffer.size()); i += t_size) {
             const_binary_reference view(buffer.data() + i, t_size);
             vec.emplace_back(std::move(from_binary_view<element_type>(view)));
         }
diff --git a/include/parallelzone/runtime/resource_set.hpp b/include/parallelzone/runtime/resource_set.hpp
index fc02843d..94d07c8d 100644
--- a/include/parallelzone/runtime/resource_set.hpp
+++ b/include/parallelzone/runtime/resource_set.hpp
@@ -22,7 +22,7 @@
 namespace parallelzone::runtime {
 
 namespace detail_ {
-class ResourceSetPIMPL;
+struct ResourceSetPIMPL;
 }
 
 /** @brief A set of runtime resources.
diff --git a/include/parallelzone/runtime/runtime_view.hpp b/include/parallelzone/runtime/runtime_view.hpp
index 14164b54..8cd51aed 100644
--- a/include/parallelzone/runtime/runtime_view.hpp
+++ b/include/parallelzone/runtime/runtime_view.hpp
@@ -21,7 +21,7 @@
 
 namespace parallelzone::runtime {
 namespace detail_ {
-class RuntimeViewPIMPL;
+struct RuntimeViewPIMPL;
 }
 
 /** @brief A view of the execution environment.
diff --git a/src/parallelzone/runtime/resource_set.cpp b/src/parallelzone/runtime/resource_set.cpp
index 0db05d22..0aa1ce6a 100644
--- a/src/parallelzone/runtime/resource_set.cpp
+++ b/src/parallelzone/runtime/resource_set.cpp
@@ -51,8 +51,8 @@ ResourceSet::size_type ResourceSet::mpi_rank() const noexcept {
 
 bool ResourceSet::is_mine() const noexcept {
     if(!has_pimpl_()) return false;
-    if(mpi_rank() == MPI_PROC_NULL) return false;
-    return m_pimpl_->m_my_mpi.me() == mpi_rank();
+    if(mpi_rank() == size_type(MPI_PROC_NULL)) return false;
+    return size_type(m_pimpl_->m_my_mpi.me()) == mpi_rank();
 }
 
 bool ResourceSet::has_ram() const noexcept { return has_pimpl_() && !null(); }
@@ -71,7 +71,9 @@ ResourceSet::logger_reference ResourceSet::logger() const {
 // -- Utility methods
 // -----------------------------------------------------------------------------
 
-bool ResourceSet::null() const noexcept { return mpi_rank() == MPI_PROC_NULL; }
+bool ResourceSet::null() const noexcept {
+    return mpi_rank() == size_type(MPI_PROC_NULL);
+}
 
 bool ResourceSet::empty() const noexcept {
     // TODO: Need to check for loggers
diff --git a/tests/cxx/doc_snippets/quickstart.cpp b/tests/cxx/doc_snippets/quickstart.cpp
index 8378ddd2..1a7a7ccb 100644
--- a/tests/cxx/doc_snippets/quickstart.cpp
+++ b/tests/cxx/doc_snippets/quickstart.cpp
@@ -50,6 +50,7 @@ TEST_CASE("quick start") {
     // Figure out how much RAM the local process has access to
     const auto my_ram = my_rs.ram().total_space();
 
+    REQUIRE(my_ram >= 0);
     REQUIRE(n_rs > 0);
     if(my_rs_rank == 0) {
         REQUIRE(ranks_on_0);
diff --git a/tests/cxx/doc_snippets/ram.cpp b/tests/cxx/doc_snippets/ram.cpp
index 78dff63e..f0821665 100644
--- a/tests/cxx/doc_snippets/ram.cpp
+++ b/tests/cxx/doc_snippets/ram.cpp
@@ -57,4 +57,6 @@ TEST_CASE("ram") {
     } else {
         REQUIRE_FALSE(all_data);
     }
+    REQUIRE(rank_0_total >= 0);
+    REQUIRE(my_total_ram >= 0);
 }
diff --git a/tests/cxx/doc_snippets/resource_set.cpp b/tests/cxx/doc_snippets/resource_set.cpp
index 55c7c540..b66f93b9 100644
--- a/tests/cxx/doc_snippets/resource_set.cpp
+++ b/tests/cxx/doc_snippets/resource_set.cpp
@@ -57,4 +57,6 @@ TEST_CASE("resource_set") {
     REQUIRE(is_local == am_i_supposed_to_be_0);
     REQUIRE(do_i_have_ram);
     REQUIRE(does_0_have_ram);
+    REQUIRE(my_ram.total_space() >= 0);
+    REQUIRE(ram_0.total_space() >= 0);
 }
diff --git a/tests/cxx/unit_tests/parallelzone/hardware/ram/ram.cpp b/tests/cxx/unit_tests/parallelzone/hardware/ram/ram.cpp
index b68b4718..f0e71019 100644
--- a/tests/cxx/unit_tests/parallelzone/hardware/ram/ram.cpp
+++ b/tests/cxx/unit_tests/parallelzone/hardware/ram/ram.cpp
@@ -30,7 +30,6 @@ TEST_CASE("RAM") {
     using size_type = ram_type::size_type;
     const auto& run = testing::PZEnvironment::comm_world();
     const auto& rs  = run.my_resource_set();
-    auto my_rank    = rs.mpi_rank();
 
     RAM defaulted;
     RAM has_value = rs.ram();
diff --git a/tests/cxx/unit_tests/parallelzone/logging/detail_/spdlog/spdlog.cpp b/tests/cxx/unit_tests/parallelzone/logging/detail_/spdlog/spdlog.cpp
index 7a1b1113..fb055004 100644
--- a/tests/cxx/unit_tests/parallelzone/logging/detail_/spdlog/spdlog.cpp
+++ b/tests/cxx/unit_tests/parallelzone/logging/detail_/spdlog/spdlog.cpp
@@ -51,7 +51,7 @@ TEST_CASE("SpdlogPIMPL") {
                                          severity::info,  severity::warn,
                                          severity::error, severity::critical};
 
-        for(auto i = 0; i < all_levels.size(); ++i) {
+        for(decltype(all_levels.size()) i = 0; i < all_levels.size(); ++i) {
             SECTION("level = " + std::to_string(i)) {
                 ss_log.set_severity(all_levels[i]);
                 ss_log.log(severity::trace, "Hello trace");
diff --git a/tests/cxx/unit_tests/parallelzone/mpi_helpers/binary_buffer/binary_view.cpp b/tests/cxx/unit_tests/parallelzone/mpi_helpers/binary_buffer/binary_view.cpp
index 067b37a6..95176eae 100644
--- a/tests/cxx/unit_tests/parallelzone/mpi_helpers/binary_buffer/binary_view.cpp
+++ b/tests/cxx/unit_tests/parallelzone/mpi_helpers/binary_buffer/binary_view.cpp
@@ -31,7 +31,6 @@ namespace {
 template<typename T>
 auto byte_data(T&& input) {
     using const_pointer = BinaryView::const_pointer;
-    using size_type     = BinaryView::size_type;
     using clean_type    = std::decay_t<T>;
     auto p              = reinterpret_cast<const_pointer>(input.data());
     auto n = input.size() * sizeof(typename clean_type::value_type);
diff --git a/tests/cxx/unit_tests/parallelzone/mpi_helpers/commpp/commpp.cpp b/tests/cxx/unit_tests/parallelzone/mpi_helpers/commpp/commpp.cpp
index 0da631b7..667291c0 100644
--- a/tests/cxx/unit_tests/parallelzone/mpi_helpers/commpp/commpp.cpp
+++ b/tests/cxx/unit_tests/parallelzone/mpi_helpers/commpp/commpp.cpp
@@ -22,9 +22,6 @@ using size_type     = std::size_t;
 using opt_root_type = std::optional<size_type>;
 
 TEST_CASE("CommPP") {
-    using value_type      = CommPP::binary_type;
-    using const_reference = CommPP::const_binary_reference;
-
     auto& world = testing::PZEnvironment::comm_world();
 
     CommPP defaulted;
@@ -35,8 +32,8 @@ TEST_CASE("CommPP") {
     MPI_Comm_size(comm.comm(), &corr_size);
     MPI_Comm_rank(comm.comm(), &corr_rank);
 
-    auto n_ranks = comm.size();
-    auto me      = comm.me();
+    auto n_ranks = size_type(comm.size());
+    auto me      = size_type(comm.me());
 
     SECTION("CTors") {
         SECTION("Default") {
@@ -125,13 +122,13 @@ TEST_CASE("CommPP") {
     SECTION("size()") {
         REQUIRE(defaulted.size() == 0);
         REQUIRE(null.size() == 0);
-        REQUIRE(n_ranks == corr_size);
+        REQUIRE(n_ranks == size_type(corr_size));
     }
 
     SECTION("me()") {
         REQUIRE(defaulted.me() == MPI_PROC_NULL);
         REQUIRE(null.me() == MPI_PROC_NULL);
-        REQUIRE(me == corr_rank);
+        REQUIRE(me == size_type(corr_rank));
     }
 
     SECTION("swap") {
@@ -168,16 +165,15 @@ TEST_CASE("CommPP") {
     // These loops test various MPI operations under different roots and
     // different message sizes.
 
-    // All of these types must be constructible given a single std::size_t
-    const int max_ranks              = 5;
-    const std::size_t max_chunk_size = 5;
-    using needs_serialized           = std::string;
-    using no_serialization           = double;
+    // All of these types must be constructible given a single size_type
+    const size_type max_ranks      = 5;
+    const size_type max_chunk_size = 5;
+    using needs_serialized         = std::string;
+    using no_serialization         = double;
 
-    for(std::size_t chunk_size = 1; chunk_size < max_chunk_size; ++chunk_size) {
+    for(size_type chunk_size = 1; chunk_size < max_chunk_size; ++chunk_size) {
         auto chunk_str = " chunk = " + std::to_string(chunk_size);
         auto begin     = me * chunk_size;
-        auto end       = begin + chunk_size;
 
         SECTION("all gather" + chunk_str) {
             SECTION("needs serialized") {
@@ -205,7 +201,7 @@ TEST_CASE("CommPP") {
                 data_type local_data(chunk_size * me, "Hello");
                 auto rv = comm.gatherv(local_data);
                 std::vector<data_type> corr;
-                for(std::size_t i = 0; i < n_ranks; ++i) {
+                for(size_type i = 0; i < n_ranks; ++i) {
                     corr.emplace_back(data_type(chunk_size * i, "Hello"));
                 }
                 REQUIRE(rv == corr);
@@ -240,7 +236,7 @@ TEST_CASE("CommPP") {
             REQUIRE(rv == corr);
         }
 
-        for(std::size_t root = 0; root < std::min(n_ranks, max_ranks); ++root) {
+        for(size_type root = 0; root < std::min(n_ranks, max_ranks); ++root) {
             auto root_str = " root = " + std::to_string(root);
 
             SECTION("gather " + root_str + chunk_str) {
@@ -281,7 +277,7 @@ TEST_CASE("CommPP") {
 
                     if(me == root) {
                         std::vector<data_type> corr;
-                        for(std::size_t i = 0; i < n_ranks; ++i) {
+                        for(size_type i = 0; i < n_ranks; ++i) {
                             corr.emplace_back(
                               data_type(chunk_size * i, "Hello"));
                         }
diff --git a/tests/cxx/unit_tests/parallelzone/mpi_helpers/commpp/detail_/commpp_pimpl.cpp b/tests/cxx/unit_tests/parallelzone/mpi_helpers/commpp/detail_/commpp_pimpl.cpp
index 27145b7a..fd8f2654 100644
--- a/tests/cxx/unit_tests/parallelzone/mpi_helpers/commpp/detail_/commpp_pimpl.cpp
+++ b/tests/cxx/unit_tests/parallelzone/mpi_helpers/commpp/detail_/commpp_pimpl.cpp
@@ -49,9 +49,7 @@ auto make_data(std::size_t min, std::size_t max) {
  */
 template<typename T>
 void gather_kernel(std::size_t chunk_size, root_type root, pimpl_type& comm) {
-    using reference       = pimpl_type::binary_reference;
     using const_reference = pimpl_type::const_binary_reference;
-    using size_type       = std::size_t;
 
     auto am_i_root = root.has_value() ? comm.me() == *root : true;
     auto data      = make_data<T>(0, chunk_size * comm.size());
@@ -83,7 +81,6 @@ void gather_buffer_kernel(std::size_t chunk_size, root_type root,
                           pimpl_type& comm) {
     using reference       = pimpl_type::binary_reference;
     using const_reference = pimpl_type::const_binary_reference;
-    using size_type       = std::size_t;
 
     bool am_i_root = root.has_value() ? comm.me() == *root : true;
 
@@ -128,7 +125,7 @@ void gatherv_kernel(std::size_t chunk_size, root_type root, pimpl_type& comm) {
         REQUIRE(rv.has_value());
         std::vector<T> corr;
         std::vector<int> sizes_corr; // Sizes (in bytes)
-        for(std::size_t rank = 0; rank < n_ranks; ++rank) {
+        for(std::size_t rank = 0; rank < std::size_t(n_ranks); ++rank) {
             sizes_corr.push_back((chunk_size + rank) * sizeof(T));
             for(std::size_t i = 0; i < chunk_size + rank; ++i)
                 corr.push_back(T(i + 1));
@@ -202,7 +199,8 @@ TEST_CASE("CommPPPIMPL") {
             gatherv_kernel<double>(chunk_size, std::nullopt, comm);
         }
 
-        for(std::size_t root = 0; root < std::min(n_ranks, 5); ++root) {
+        std::size_t min = std::min(n_ranks, 5);
+        for(std::size_t root = 0; root < min; ++root) {
             auto root_str = " root = " + std::to_string(root);
             SECTION("gather" + root_str + chunk_str) {
                 gather_kernel<std::byte>(chunk_size, root, comm);
diff --git a/tests/cxx/unit_tests/parallelzone/runtime/resource_set.cpp b/tests/cxx/unit_tests/parallelzone/runtime/resource_set.cpp
index ffa8f615..8d25d0c5 100644
--- a/tests/cxx/unit_tests/parallelzone/runtime/resource_set.cpp
+++ b/tests/cxx/unit_tests/parallelzone/runtime/resource_set.cpp
@@ -28,10 +28,11 @@ using namespace parallelzone::runtime;
  *
  */
 TEST_CASE("ResourceSet") {
-    using pimpl_type     = ResourceSet::pimpl_type;
-    using comm_type      = parallelzone::mpi_helpers::CommPP;
-    using logger_type    = ResourceSet::logger_type;
-    const auto null_rank = MPI_PROC_NULL;
+    using pimpl_type  = ResourceSet::pimpl_type;
+    using comm_type   = parallelzone::mpi_helpers::CommPP;
+    using logger_type = ResourceSet::logger_type;
+    using size_type   = ResourceSet::size_type;
+    const size_type null_rank(MPI_PROC_NULL);
 
     logger_type log;
 
@@ -59,7 +60,7 @@ TEST_CASE("ResourceSet") {
             REQUIRE_FALSE(null.is_mine());
             REQUIRE_FALSE(null.has_ram());
 
-            REQUIRE(rs.mpi_rank() == comm.me());
+            REQUIRE(rs.mpi_rank() == size_type(comm.me()));
             REQUIRE(rs.is_mine());
             REQUIRE(rs.has_ram()); // I presume all computers have RAM...
         }
@@ -112,7 +113,7 @@ TEST_CASE("ResourceSet") {
     SECTION("mpi_rank") {
         REQUIRE(defaulted.mpi_rank() == null_rank);
         REQUIRE(null.mpi_rank() == null_rank);
-        REQUIRE(rs.mpi_rank() == comm.me());
+        REQUIRE(rs.mpi_rank() == size_type(comm.me()));
     }
 
     SECTION("is_mine") {
diff --git a/tests/cxx/unit_tests/parallelzone/runtime/runtime_view.cpp b/tests/cxx/unit_tests/parallelzone/runtime/runtime_view.cpp
index 53b6304c..af25079f 100644
--- a/tests/cxx/unit_tests/parallelzone/runtime/runtime_view.cpp
+++ b/tests/cxx/unit_tests/parallelzone/runtime/runtime_view.cpp
@@ -164,7 +164,7 @@ TEST_CASE("RuntimeView") {
         REQUIRE_THROWS_AS(null.at(0), std::out_of_range);
         auto n_resource_sets = defaulted.size();
         logger_type log;
-        for(auto i = 0; i < n_resource_sets; ++i) {
+        for(decltype(n_resource_sets) i = 0; i < n_resource_sets; ++i) {
             auto corr = runtime::detail_::make_resource_set(i, comm, log);
             REQUIRE(defaulted.at(i) == corr);
             REQUIRE(argc_argv.at(i) == corr);