diff --git a/modules/calib3d/src/five-point.cpp b/modules/calib3d/src/five-point.cpp
index 3816e91263..5af82bde77 100644
--- a/modules/calib3d/src/five-point.cpp
+++ b/modules/calib3d/src/five-point.cpp
@@ -30,7 +30,6 @@
 */
 
 #include "precomp.hpp"
-#include <complex>
 
 namespace cv
 {
@@ -101,7 +100,7 @@ public:
         c[1] = (b[29]*b[7]*b[24]-b[29]*b[20]*b[11]+b[2]*b[20]*b[38]-b[2]*b[25]*b[33]-b[28]*b[20]*b[12]+b[28]*b[7]*b[25]-b[29]*b[19]*b[12]-b[3]*b[24]*b[33]+b[15]*b[33]*b[12]+b[3]*b[19]*b[38]-b[16]*b[6]*b[38]+b[3]*b[20]*b[37]+b[16]*b[32]*b[12]+b[29]*b[6]*b[25]-b[16]*b[7]*b[37]-b[3]*b[25]*b[32]-b[15]*b[7]*b[38]+b[16]*b[33]*b[11]);
         c[0] = -b[29]*b[20]*b[12]+b[29]*b[7]*b[25]+b[16]*b[33]*b[12]-b[16]*b[7]*b[38]+b[3]*b[20]*b[38]-b[3]*b[25]*b[33];
 
-        std::vector<std::complex<double> > roots;
+        std::vector<Complex<double> > roots;
         solvePoly(coeffs, roots);
 
         std::vector<double> xs, ys, zs;
@@ -111,8 +110,8 @@ public:
         double* e = ematrix.ptr<double>();
         for (size_t i = 0; i < roots.size(); i++)
         {
-            if (fabs(roots[i].imag()) > 1e-10) continue;
-            double z1 = roots[i].real();
+            if (fabs(roots[i].im) > 1e-10) continue;
+            double z1 = roots[i].re;
             double z2 = z1 * z1;
             double z3 = z2 * z1;
             double z4 = z3 * z1;
diff --git a/modules/core/include/opencv2/core/cvstd.inl.hpp b/modules/core/include/opencv2/core/cvstd.inl.hpp
index ab278bb6e7..3f29a1b675 100644
--- a/modules/core/include/opencv2/core/cvstd.inl.hpp
+++ b/modules/core/include/opencv2/core/cvstd.inl.hpp
@@ -45,6 +45,7 @@
 #define __OPENCV_CORE_CVSTDINL_HPP__
 
 #ifndef OPENCV_NOSTL
+#  include <complex>
 #  include <ostream>
 #endif
 
diff --git a/modules/core/include/opencv2/core/types.hpp b/modules/core/include/opencv2/core/types.hpp
index 8add1dc2f1..e5708d2795 100644
--- a/modules/core/include/opencv2/core/types.hpp
+++ b/modules/core/include/opencv2/core/types.hpp
@@ -52,10 +52,6 @@
 #include <cfloat>
 #include <vector>
 
-#ifndef OPENCV_NOSTL
-#  include <complex>
-#endif
-
 #include "opencv2/core/cvdef.h"
 #include "opencv2/core/cvstd.hpp"
 #include "opencv2/core/matx.hpp"
diff --git a/modules/ocl/src/fft.cpp b/modules/ocl/src/fft.cpp
index 5edd07bb3f..d84d01a5bf 100644
--- a/modules/ocl/src/fft.cpp
+++ b/modules/ocl/src/fft.cpp
@@ -180,19 +180,19 @@ cv::ocl::FftPlan::FftPlan(Size _dft_size, int _src_step, int _dst_step, int _fla
     case C2C:
         inLayout        = CLFFT_COMPLEX_INTERLEAVED;
         outLayout       = CLFFT_COMPLEX_INTERLEAVED;
-        clStridesIn[1]  = src_step / sizeof(std::complex<float>);
+        clStridesIn[1]  = src_step / (2*sizeof(float));
         clStridesOut[1] = clStridesIn[1];
         break;
     case R2C:
         inLayout        = CLFFT_REAL;
         outLayout       = CLFFT_HERMITIAN_INTERLEAVED;
         clStridesIn[1]  = src_step / sizeof(float);
-        clStridesOut[1] = dst_step / sizeof(std::complex<float>);
+        clStridesOut[1] = dst_step / (2*sizeof(float));
         break;
     case C2R:
         inLayout        = CLFFT_HERMITIAN_INTERLEAVED;
         outLayout       = CLFFT_REAL;
-        clStridesIn[1]  = src_step / sizeof(std::complex<float>);
+        clStridesIn[1]  = src_step / (2*sizeof(float));
         clStridesOut[1] = dst_step / sizeof(float);
         break;
     default:
diff --git a/modules/ocl/src/gemm.cpp b/modules/ocl/src/gemm.cpp
index 840f6285cc..c5e14bffd7 100644
--- a/modules/ocl/src/gemm.cpp
+++ b/modules/ocl/src/gemm.cpp
@@ -121,12 +121,12 @@ void cv::ocl::gemm(const oclMat &src1, const oclMat &src2, double alpha,
         break;
     case CV_32FC2:
     {
-        lda  /= sizeof(std::complex<float>);
-        ldb  /= sizeof(std::complex<float>);
-        ldc  /= sizeof(std::complex<float>);
-        offa /= sizeof(std::complex<float>);
-        offb /= sizeof(std::complex<float>);
-        offc /= sizeof(std::complex<float>);
+        lda  /= (2*sizeof(float));
+        ldb  /= (2*sizeof(float));
+        ldc  /= (2*sizeof(float));
+        offa /= (2*sizeof(float));
+        offb /= (2*sizeof(float));
+        offc /= (2*sizeof(float));
         cl_float2 alpha_2 = {{alpha, 0}};
         cl_float2 beta_2  = {{beta, 0}};
         openCLSafeCall
@@ -139,12 +139,12 @@ void cv::ocl::gemm(const oclMat &src1, const oclMat &src2, double alpha,
     break;
     case CV_64FC2:
     {
-        lda  /= sizeof(std::complex<double>);
-        ldb  /= sizeof(std::complex<double>);
-        ldc  /= sizeof(std::complex<double>);
-        offa /= sizeof(std::complex<double>);
-        offb /= sizeof(std::complex<double>);
-        offc /= sizeof(std::complex<double>);
+        lda  /= (2*sizeof(double));
+        ldb  /= (2*sizeof(double));
+        ldc  /= (2*sizeof(double));
+        offa /= (2*sizeof(double));
+        offb /= (2*sizeof(double));
+        offc /= (2*sizeof(double));
         cl_double2 alpha_2 = {{alpha, 0}};
         cl_double2 beta_2  = {{beta, 0}};
         openCLSafeCall