diff --git a/include/alpaka/test/KernelExecutionFixture.hpp b/include/alpaka/test/KernelExecutionFixture.hpp
index 954cadbb31f6..8d783be62186 100644
--- a/include/alpaka/test/KernelExecutionFixture.hpp
+++ b/include/alpaka/test/KernelExecutionFixture.hpp
@@ -1,4 +1,4 @@
-/* Copyright 2022 Benjamin Worpitz, Andrea Bocci, Bernhard Manfred Gruber
+/* Copyright 2023 Benjamin Worpitz, Andrea Bocci, Bernhard Manfred Gruber, Jan Stephan
  * SPDX-License-Identifier: MPL-2.0
  */
 
@@ -25,6 +25,13 @@ namespace alpaka::test
     template<typename TAcc>
     class KernelExecutionFixture
     {
+#if defined(BOOST_COMP_GNUC) && BOOST_COMP_GNUC >= BOOST_VERSION_NUMBER(11, 0, 0)                                     \
+    && BOOST_COMP_GNUC < BOOST_VERSION_NUMBER(12, 0, 0)
+// g++-11 (wrongly) believes that m_platformHost is used in an uninitialized state.
+#    pragma GCC diagnostic push
+#    pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
+
     public:
         using Acc = TAcc;
         using Dim = alpaka::Dim<Acc>;
@@ -34,25 +41,18 @@ namespace alpaka::test
         using Queue = test::DefaultQueue<Device>;
         using WorkDiv = WorkDivMembers<Dim, Idx>;
 
-        KernelExecutionFixture(WorkDiv workDiv)
-            : m_devHost{getDevByIdx(m_platformHost, 0)}
-            , m_device{getDevByIdx(m_platform, 0)}
-            , m_queue{m_device}
-            , m_workDiv{std::move(workDiv)}
+        KernelExecutionFixture(WorkDiv workDiv) : m_workDiv{std::move(workDiv)}
         {
         }
 
         template<typename TExtent>
         KernelExecutionFixture(TExtent const& extent)
-            : m_devHost{getDevByIdx(m_platformHost, 0)}
-            , m_device{getDevByIdx(m_platform, 0)}
-            , m_queue{m_device}
-            , m_workDiv{getValidWorkDiv<Acc>(
-                  m_device,
-                  extent,
-                  Vec<Dim, Idx>::ones(),
-                  false,
-                  GridBlockExtentSubDivRestrictions::Unrestricted)}
+            : m_workDiv{getValidWorkDiv<Acc>(
+                m_device,
+                extent,
+                Vec<Dim, Idx>::ones(),
+                false,
+                GridBlockExtentSubDivRestrictions::Unrestricted)}
         {
         }
 
@@ -76,11 +76,15 @@ namespace alpaka::test
         }
 
     private:
-        PlatformCpu m_platformHost;
-        DevCpu m_devHost;
-        Platform m_platform;
-        Device m_device;
-        Queue m_queue;
+        PlatformCpu m_platformHost{};
+        DevCpu m_devHost{getDevByIdx(m_platformHost, 0)};
+        Platform m_platform{};
+        Device m_device{getDevByIdx(m_platform, 0)};
+        Queue m_queue{m_device};
         WorkDiv m_workDiv;
+#if defined(BOOST_COMP_GNUC) && BOOST_COMP_GNUC >= BOOST_VERSION_NUMBER(11, 0, 0)                                     \
+    && BOOST_COMP_GNUC < BOOST_VERSION_NUMBER(12, 0, 0)
+#    pragma GCC diagnostic pop
+#endif
     };
 } // namespace alpaka::test
diff --git a/include/alpaka/test/queue/QueueTestFixture.hpp b/include/alpaka/test/queue/QueueTestFixture.hpp
index d2c755976e9c..3f6e57160f0d 100644
--- a/include/alpaka/test/queue/QueueTestFixture.hpp
+++ b/include/alpaka/test/queue/QueueTestFixture.hpp
@@ -1,4 +1,4 @@
-/* Copyright 2019 Benjamin Worpitz
+/* Copyright 2023 Benjamin Worpitz, Jan Stephan
  * SPDX-License-Identifier: MPL-2.0
  */
 
@@ -12,16 +12,24 @@ namespace alpaka::test
     template<typename TDevQueue>
     struct QueueTestFixture
     {
+#if defined(BOOST_COMP_GNUC) && BOOST_COMP_GNUC >= BOOST_VERSION_NUMBER(11, 0, 0)                                     \
+    && BOOST_COMP_GNUC < BOOST_VERSION_NUMBER(12, 0, 0)
+// g++-11 (wrongly) believes that m_platform is used in an uninitialized state.
+#    pragma GCC diagnostic push
+#    pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
         using Dev = std::tuple_element_t<0, TDevQueue>;
         using Queue = std::tuple_element_t<1, TDevQueue>;
         using Platform = alpaka::Platform<Dev>;
 
-        QueueTestFixture() : m_dev(getDevByIdx(m_platform, 0)), m_queue(m_dev)
-        {
-        }
+        QueueTestFixture() = default;
 
-        Platform m_platform;
-        Dev m_dev;
-        Queue m_queue;
+        Platform m_platform{};
+        Dev m_dev{getDevByIdx(m_platform, 0)};
+        Queue m_queue{m_dev};
+#if defined(BOOST_COMP_GNUC) && BOOST_COMP_GNUC >= BOOST_VERSION_NUMBER(11, 0, 0)                                     \
+    && BOOST_COMP_GNUC < BOOST_VERSION_NUMBER(12, 0, 0)
+#    pragma GCC diagnostic pop
+#endif
     };
 } // namespace alpaka::test
diff --git a/test/unit/mem/copy/src/BufSlicing.cpp b/test/unit/mem/copy/src/BufSlicing.cpp
index f3a2374b1143..f690acd7e8e9 100644
--- a/test/unit/mem/copy/src/BufSlicing.cpp
+++ b/test/unit/mem/copy/src/BufSlicing.cpp
@@ -1,4 +1,4 @@
-/* Copyright 2023 Axel Huebl, Benjamin Worpitz, Jakob Krude, Bernhard Manfred Gruber, Jan Stephan, Andrea Bocci
+/* Copyright 2023 Axel Hübl, Benjamin Worpitz, Jakob Krude, Bernhard Manfred Gruber, Jan Stephan, Andrea Bocci
  * SPDX-License-Identifier: MPL-2.0
  */
 
@@ -20,6 +20,12 @@
 template<typename TDim, typename TIdx, typename TAcc, typename TData, typename Vec = alpaka::Vec<TDim, TIdx>>
 struct TestContainer
 {
+#if defined(BOOST_COMP_GNUC) && BOOST_COMP_GNUC >= BOOST_VERSION_NUMBER(11, 0, 0)                                     \
+    && BOOST_COMP_GNUC < BOOST_VERSION_NUMBER(12, 0, 0)
+// g++-11 (wrongly) believes that platformHost is used in an uninitialized state.
+#    pragma GCC diagnostic push
+#    pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
     using AccQueueProperty = alpaka::Blocking;
     using DevQueue = alpaka::Queue<TAcc, AccQueueProperty>;
     using DevAcc = alpaka::Dev<TAcc>;
@@ -33,19 +39,13 @@ struct TestContainer
 
     using SubView = alpaka::ViewSubView<DevAcc, TData, TDim, TIdx>;
 
-    PlatformAcc const platformAcc{};
-    DevAcc const devAcc;
-    PlatformHost const platformHost{};
-    DevHost const devHost;
-    DevQueue devQueue;
-
-    // Constructor
-    TestContainer()
-        : devAcc(alpaka::getDevByIdx(platformAcc, 0))
-        , devHost(alpaka::getDevByIdx(platformHost, 0u))
-        , devQueue(devAcc)
-    {
-    }
+    PlatformAcc platformAcc{};
+    DevAcc devAcc{alpaka::getDevByIdx(platformAcc, 0)};
+    PlatformHost platformHost{};
+    DevHost devHost{alpaka::getDevByIdx(platformHost, 0u)};
+    DevQueue devQueue{devAcc};
+
+    TestContainer() = default;
 
     auto createHostBuffer(Vec extents, bool indexed) -> BufHost
     {
@@ -108,6 +108,10 @@ struct TestContainer
             REQUIRE(ptrA[i] == Catch::Approx(ptrB[i]));
         }
     }
+#if defined(BOOST_COMP_GNUC) && BOOST_COMP_GNUC >= BOOST_VERSION_NUMBER(11, 0, 0)                                     \
+    && BOOST_COMP_GNUC < BOOST_VERSION_NUMBER(12, 0, 0)
+#    pragma GCC diagnostic pop
+#endif
 };
 
 using DataTypes = std::tuple<int, float, double>;