diff --git a/modules/gpu/src/cuda/matrix_reductions.cu b/modules/gpu/src/cuda/matrix_reductions.cu
index 9e0e7f86c3..c970efafcd 100644
--- a/modules/gpu/src/cuda/matrix_reductions.cu
+++ b/modules/gpu/src/cuda/matrix_reductions.cu
@@ -938,7 +938,7 @@ namespace cv { namespace gpu { namespace mathfunc
     //////////////////////////////////////////////////////////////////////////
     // Sum
 
-    namespace sum 
+    namespace sums 
     {
 
     template <typename T> struct SumType {};
diff --git a/modules/gpu/src/matrix_reductions.cpp b/modules/gpu/src/matrix_reductions.cpp
index abfc89476f..151f1bfcac 100644
--- a/modules/gpu/src/matrix_reductions.cpp
+++ b/modules/gpu/src/matrix_reductions.cpp
@@ -130,7 +130,7 @@ namespace cv { namespace gpu { namespace mathfunc
     template <typename T>
     void sqrSumMultipassCaller(const DevMem2D src, PtrStep buf, double* sum, int cn);
 
-    namespace sum
+    namespace sums
     {
         void getBufSizeRequired(int cols, int rows, int cn, int& bufcols, int& bufrows);
     }
@@ -161,8 +161,8 @@ Scalar cv::gpu::sum(const GpuMat& src, GpuMat& buf)
             sumCaller<int>, sumCaller<float>, 0 };
 
     Size buf_size;
-    sum::getBufSizeRequired(src.cols, src.rows, src.channels(), 
-                               buf_size.width, buf_size.height); 
+    sums::getBufSizeRequired(src.cols, src.rows, src.channels(), 
+                            buf_size.width, buf_size.height); 
     ensureSizeIsEnough(buf_size, CV_8U, buf);
 
     Caller* callers = multipass_callers;
@@ -206,8 +206,8 @@ Scalar cv::gpu::sqrSum(const GpuMat& src, GpuMat& buf)
         callers = singlepass_callers;
 
     Size buf_size;
-    sum::getBufSizeRequired(src.cols, src.rows, src.channels(), 
-                               buf_size.width, buf_size.height); 
+    sums::getBufSizeRequired(src.cols, src.rows, src.channels(), 
+                             buf_size.width, buf_size.height); 
     ensureSizeIsEnough(buf_size, CV_8U, buf);
 
     Caller caller = callers[src.depth()];