diff --git a/Framework/HistogramData/test/HistogramIteratorTest.h b/Framework/HistogramData/test/HistogramIteratorTest.h
index 6d1d1f361ff50763f01f2295ef851fb63e7f0149..202214eb22bb9dbceeb1e05617bc1d1056e47dcb 100644
--- a/Framework/HistogramData/test/HistogramIteratorTest.h
+++ b/Framework/HistogramData/test/HistogramIteratorTest.h
@@ -301,9 +301,10 @@ public:
 
   void test_convert_counts_to_frequency_for_each_item_sparse() {
     double total = 0;
+    double floor = static_cast<double>(histSize) - 5.0;
     for (size_t i = 0; i < nHists; i++) {
       for (auto &item : m_hist) {
-        if (item.counts() > histSize - 5)
+        if (item.counts() > floor)
           total += item.frequency();
       }
     }
@@ -311,11 +312,12 @@ public:
 
   void test_convert_counts_to_frequency_once_per_histogram_sparse() {
     double total = 0;
+    double floor = static_cast<double>(histSize) - 5.0;
     for (size_t i = 0; i < nHists; i++) {
       const auto &counts = m_hist.counts();
       const auto &frequencies = m_hist.frequencies();
       for (size_t j = 0; j < histSize; ++j)
-        if (counts[j] > histSize - 5)
+        if (counts[j] > floor)
           total += frequencies[j];
     }
   }
diff --git a/buildconfig/CMake/GoogleTest.in b/buildconfig/CMake/GoogleTest.in
index e37efa6f5bfca2f3074140a7607c69afd960982e..df7efa94f075f6b159b61bdcf6c3cdf8d65e1d24 100644
--- a/buildconfig/CMake/GoogleTest.in
+++ b/buildconfig/CMake/GoogleTest.in
@@ -16,6 +16,7 @@ ExternalProject_Add(googletest
             COMMAND "@GIT_EXECUTABLE@" apply --whitespace fix "@CMAKE_SOURCE_DIR@/buildconfig/CMake/googletest_override.patch"
             COMMAND "@GIT_EXECUTABLE@" apply --whitespace fix "@CMAKE_SOURCE_DIR@/buildconfig/CMake/googletest_static.patch"
             COMMAND "@GIT_EXECUTABLE@" apply --whitespace fix "@CMAKE_SOURCE_DIR@/buildconfig/CMake/googletest_msvc_cpp11.patch"
+            COMMAND "@GIT_EXECUTABLE@" apply --whitespace fix "@CMAKE_SOURCE_DIR@/buildconfig/CMake/googletest_wconversion.patch"
   CONFIGURE_COMMAND ""
   BUILD_COMMAND     ""
   INSTALL_COMMAND   ""
diff --git a/buildconfig/CMake/googletest_wconversion.patch b/buildconfig/CMake/googletest_wconversion.patch
new file mode 100644
index 0000000000000000000000000000000000000000..3ba9d824fb3ef7ec4430da491c5d2eb057d66d3b
--- /dev/null
+++ b/buildconfig/CMake/googletest_wconversion.patch
@@ -0,0 +1,19 @@
+diff --git a/googlemock/include/gmock/gmock-matchers.h b/googlemock/include/gmock/gmock-matchers.h
+index 33b37a7..fbb5734 100644
+--- a/googlemock/include/gmock/gmock-matchers.h
++++ b/googlemock/include/gmock/gmock-matchers.h
+@@ -1620,8 +1620,13 @@ class VariadicMatcher {
+   }
+ 
+  private:
++#if defined(__GNUC__) && !defined(__clang__)
++#pragma GCC diagnostic ignored "-Wconversion"
++#endif
+   typedef MatcherList<sizeof...(Args), Args...> MatcherListType;
+-
++#if defined(__GNUC__) && !defined(__clang__)
++#pragma GCC diagnostic warning "-Wconversion"
++#endif
+   const typename MatcherListType::ListType matchers_;
+ 
+   GTEST_DISALLOW_ASSIGN_(VariadicMatcher);
diff --git a/qt/scientific_interfaces/ISISReflectometry/ReflDataProcessorPresenter.cpp b/qt/scientific_interfaces/ISISReflectometry/ReflDataProcessorPresenter.cpp
index 01313843844aeb9d1770c758ec1b8888e07771af..8f7bc3fc7427f19bf0634720c75fb3633cca4bd8 100644
--- a/qt/scientific_interfaces/ISISReflectometry/ReflDataProcessorPresenter.cpp
+++ b/qt/scientific_interfaces/ISISReflectometry/ReflDataProcessorPresenter.cpp
@@ -697,7 +697,8 @@ bool ReflDataProcessorPresenter::parseUniform(TimeSlicingInfo &slicing,
   if (mws != nullptr) {
     const auto run = mws->run();
     const auto totalDuration = run.endTime() - run.startTime();
-    double totalDurationSec = totalDuration.total_seconds();
+    double totalDurationSec =
+        static_cast<double>(totalDuration.total_seconds());
     double sliceDuration = .0;
     size_t numSlices = 0;