diff --git a/src/pe/raytracing/Color.cpp b/src/pe/raytracing/Color.cpp
index c07f33a281fa313c5a9bd91bd7bdef4268d02630..29c7e6d3491eb9c041470474ec6af3c43f784a64 100644
--- a/src/pe/raytracing/Color.cpp
+++ b/src/pe/raytracing/Color.cpp
@@ -20,7 +20,9 @@
 
 #include "Color.h"
 
-using namespace walberla::pe::raytracing;
+namespace walberla {
+namespace pe {
+namespace raytracing {
 
 /*!\brief Create a Color object from HSV values.
  * \param hue Hue value in degrees from 0-360
@@ -72,3 +74,7 @@ Color Color::colorFromHSV(real_t hue, real_t saturation, real_t value) {
    
    return Color(r, g, b);
 }
+
+}
+}
+}
diff --git a/src/pe/raytracing/Raytracer.cpp b/src/pe/raytracing/Raytracer.cpp
index 400c165c9fcac3074f00ad0baa79ea88706e92de..b3793fae2f2c0f72d1f1794fdcf3cec646aeedbb 100644
--- a/src/pe/raytracing/Raytracer.cpp
+++ b/src/pe/raytracing/Raytracer.cpp
@@ -296,7 +296,7 @@ void Raytracer::writeImageToFile(const std::vector<BodyIntersectionInfo>& inters
       for (uint32_t x = 0; x < pixelsHorizontal_; x++) {
          real_t r_sum = 0, g_sum = 0, b_sum = 0;
          for (uint32_t ay = uint32_c(y)*antiAliasFactor_; ay < (uint32_c(y+1))*antiAliasFactor_; ay++) {
-            for (uint ax = x*antiAliasFactor_; ax < (x+1)*antiAliasFactor_; ax++) {
+            for (uint32_t ax = x*antiAliasFactor_; ax < (x+1)*antiAliasFactor_; ax++) {
                size_t i = coordinateToArrayIndex(ax, ay);
                r_sum += real_c(intersectionsBuffer[i].r);
                g_sum += real_c(intersectionsBuffer[i].g);