diff --git a/inst/include/RcppParallel.h b/inst/include/RcppParallel.h
index 7a5ce66d..f78a5db4 100644
--- a/inst/include/RcppParallel.h
+++ b/inst/include/RcppParallel.h
@@ -34,7 +34,7 @@ inline void parallelFor(std::size_t begin,
                         std::size_t grainSize = 1,
                         int numThreads = -1)
 {
-   grainSize = resolveValue("RCPP_PARALLEL_GRAIN_SIZE", grainSize, 1);
+   grainSize = resolveValue("RCPP_PARALLEL_GRAIN_SIZE", grainSize, 1u);
    numThreads = resolveValue("RCPP_PARALLEL_NUM_THREADS", numThreads, -1);
    
 #if RCPP_PARALLEL_USE_TBB
diff --git a/inst/include/RcppParallel/RMatrix.h b/inst/include/RcppParallel/RMatrix.h
index ca391b79..218845b8 100644
--- a/inst/include/RcppParallel/RMatrix.h
+++ b/inst/include/RcppParallel/RMatrix.h
@@ -204,7 +204,7 @@ class RMatrix {
    {
    }
 
-   inline RMatrix(const T* data, std::size_t nrow, std::size_t ncol) 
+   inline RMatrix(T* data, std::size_t nrow, std::size_t ncol) 
       : data_(data), nrow_(nrow), ncol_(ncol) 
    {
    }