diff --git a/Framework/Algorithms/src/GetDetectorOffsets.cpp b/Framework/Algorithms/src/GetDetectorOffsets.cpp
index 4567741536502ad6932633cbce493e8cbc88aecc..907e0da8ee8a717821643b0ab4af7db5d88ff593 100644
--- a/Framework/Algorithms/src/GetDetectorOffsets.cpp
+++ b/Framework/Algorithms/src/GetDetectorOffsets.cpp
@@ -98,7 +98,7 @@ void GetDetectorOffsets::exec() {
 
   m_dideal = getProperty("DIdeal");
 
-  size_t nspec = inputW->getNumberHistograms();
+  int64_t nspec = inputW->getNumberHistograms();
   // Create the output OffsetsWorkspace
   auto outputW = boost::make_shared<OffsetsWorkspace>(inputW->getInstrument());
   // Create the output MaskWorkspace
@@ -111,10 +111,10 @@ void GetDetectorOffsets::exec() {
   Progress prog(this, 0, 1.0, nspec);
   auto &spectrumInfo = maskWS->mutableSpectrumInfo();
   PARALLEL_FOR_IF(Kernel::threadSafe(*inputW))
-  for (size_t wi = 0; wi < nspec; ++wi) {
+  for (int64_t wi = 0; wi < nspec; ++wi) {
     PARALLEL_START_INTERUPT_REGION
     // Fit the peak
-    double offset = fitSpectra(static_cast<int64_t>(wi), isAbsolute);
+    double offset = fitSpectra(wi, isAbsolute);
     double mask = 0.0;
     if (std::abs(offset) > m_maxOffset) {
       offset = 0.0;
diff --git a/Framework/Algorithms/src/Stitch1D.cpp b/Framework/Algorithms/src/Stitch1D.cpp
index 1a055e5d66cfb80e5faeeb6a346061024ecf6bcb..9dba784d2424b7535c10cc0b37f459246386ce12 100644
--- a/Framework/Algorithms/src/Stitch1D.cpp
+++ b/Framework/Algorithms/src/Stitch1D.cpp
@@ -421,7 +421,7 @@ bool Stitch1D::hasNonzeroErrors(MatrixWorkspace_sptr ws) {
     PARALLEL_START_INTERUPT_REGION
     if (!hasNonZeroErrors) // Keep checking
     {
-      auto e = ws->e(static_cast<size_t>(i));
+      auto e = ws->e(i);
       auto it = std::find_if(e.begin(), e.end(), isNonzero);
       if (it != e.end()) {
         PARALLEL_CRITICAL(has_non_zero) {