diff --git a/modules/core/src/matrix.cpp b/modules/core/src/matrix.cpp
index b29dee8b76..f2ad01b2af 100644
--- a/modules/core/src/matrix.cpp
+++ b/modules/core/src/matrix.cpp
@@ -3469,9 +3469,6 @@ static bool ocl_reduce(InputArray _src, OutputArray _dst,
     if (!doubleSupport && (sdepth == CV_64F || ddepth == CV_64F))
         return false;
 
-    if ((op == CV_REDUCE_SUM && sdepth == CV_32F) || op == CV_REDUCE_MIN || op == CV_REDUCE_MAX)
-        return false;
-
     if (op == CV_REDUCE_AVG)
     {
         if (sdepth < CV_32S && ddepth < CV_32S)
diff --git a/modules/core/src/opencl/reduce2.cl b/modules/core/src/opencl/reduce2.cl
index 457378cc13..645d69867b 100644
--- a/modules/core/src/opencl/reduce2.cl
+++ b/modules/core/src/opencl/reduce2.cl
@@ -108,7 +108,10 @@ __kernel void reduce_horz_opt(__global const uchar * srcptr, int src_step, int s
         int src_index = mad24(y, src_step, mad24(x, (int)sizeof(srcT) * cn, src_offset));
 
         __global const srcT * src = (__global const srcT *)(srcptr + src_index);
-        bufT tmp[cn] = { INIT_VALUE };
+        bufT tmp[cn];
+        #pragma unroll
+        for (int c = 0; c < cn; ++c)
+            tmp[c] = INIT_VALUE;
 
         int src_step_mul = BUF_COLS * cn;
         for (int idx = x; idx < cols; idx += BUF_COLS, src += src_step_mul)
@@ -140,7 +143,10 @@ __kernel void reduce_horz_opt(__global const uchar * srcptr, int src_step, int s
         int dst_index = mad24(y, dst_step, dst_offset);
 
         __global dstT * dst = (__global dstT *)(dstptr + dst_index);
-        bufT tmp[cn] = { INIT_VALUE };
+        bufT tmp[cn];
+        #pragma unroll
+        for (int c = 0; c < cn; ++c)
+            tmp[c] = INIT_VALUE;
 
         #pragma unroll
         for (int xin = 0; xin < BUF_COLS / 2; xin ++)
@@ -179,7 +185,10 @@ __kernel void reduce(__global const uchar * srcptr, int src_step, int src_offset
         int dst_index = mad24(x, (int)sizeof(dstT0) * cn, dst_offset);
 
         __global dstT0 * dst = (__global dstT0 *)(dstptr + dst_index);
-        dstT tmp[cn] = { INIT_VALUE };
+        dstT tmp[cn];
+        #pragma unroll
+        for (int c = 0; c < cn; ++c)
+            tmp[c] = INIT_VALUE;
 
         for (int y = 0; y < rows; ++y, src_index += src_step)
         {
@@ -209,7 +218,10 @@ __kernel void reduce(__global const uchar * srcptr, int src_step, int src_offset
 
         __global const srcT * src = (__global const srcT *)(srcptr + src_index);
         __global dstT * dst = (__global dstT *)(dstptr + dst_index);
-        dstT tmp[cn] = { INIT_VALUE };
+        dstT tmp[cn];
+        #pragma unroll
+        for (int c = 0; c < cn; ++c)
+            tmp[c] = INIT_VALUE;
 
         for (int x = 0; x < cols; ++x, src += cn)
         {
diff --git a/modules/core/test/ocl/test_arithm.cpp b/modules/core/test/ocl/test_arithm.cpp
index 6e0884cb13..1e33a076e7 100644
--- a/modules/core/test/ocl/test_arithm.cpp
+++ b/modules/core/test/ocl/test_arithm.cpp
@@ -1704,7 +1704,7 @@ OCL_TEST_P(ReduceSum, Mat)
         OCL_OFF(cv::reduce(src_roi, dst_roi, dim, CV_REDUCE_SUM, dtype));
         OCL_ON(cv::reduce(usrc_roi, udst_roi, dim, CV_REDUCE_SUM, dtype));
 
-        double eps = ddepth <= CV_32S ? 1 : 1e-4;
+        double eps = ddepth <= CV_32S ? 1 : 7e-4;
         OCL_EXPECT_MATS_NEAR(dst, eps);
     }
 }