diff --git a/src/core/BubbleAnimation.cpp b/src/core/BubbleAnimation.cpp
index 4cce91782..0df70293d 100644
--- a/src/core/BubbleAnimation.cpp
+++ b/src/core/BubbleAnimation.cpp
@@ -32,7 +32,7 @@ bool BubbleAnimation::nextFrame(const QColor& head_color,
   const QPointF center(rect.center());
   const double radius = std::min(center.x() - rect.x(), center.y() - rect.y());
 
-  const double PI = imageproc::constants::PI;
+  const double PI = constants::PI;
   const double arc_fraction_as_radius = 0.25;
   // We have the following system of equations:
   // bubble_radius = arc_between_bubbles * arc_fraction_as_radius;
diff --git a/src/core/ImageMetadata.cpp b/src/core/ImageMetadata.cpp
index 92661b970..5f558876b 100644
--- a/src/core/ImageMetadata.cpp
+++ b/src/core/ImageMetadata.cpp
@@ -4,7 +4,7 @@
 #include "ImageMetadata.h"
 #include <Constants.h>
 
-using namespace imageproc::constants;
+using namespace constants;
 
 bool ImageMetadata::operator==(const ImageMetadata& other) const {
   if (m_size != other.m_size) {
diff --git a/src/core/ProjectPages.cpp b/src/core/ProjectPages.cpp
index aeb4c9728..44e8717de 100644
--- a/src/core/ProjectPages.cpp
+++ b/src/core/ProjectPages.cpp
@@ -8,6 +8,7 @@
 #include <boost/multi_index/ordered_index.hpp>
 #include <boost/multi_index/sequenced_index.hpp>
 #include <boost/multi_index_container.hpp>
+#include <cassert>
 #include <unordered_map>
 #include "AbstractRelinker.h"
 #include "ImageFileInfo.h"
diff --git a/src/core/TiffWriter.cpp b/src/core/TiffWriter.cpp
index c155ae0c1..f68b021d2 100644
--- a/src/core/TiffWriter.cpp
+++ b/src/core/TiffWriter.cpp
@@ -166,7 +166,7 @@ bool TiffWriter::writeImage(QIODevice& device, const QImage& image) {
  * Set the physical resolution, if it's defined.
  */
 void TiffWriter::setDpm(const TiffHandle& tif, const Dpm& dpm) {
-  using namespace imageproc::constants;
+  using namespace constants;
 
   if (dpm.isNull()) {
     return;
diff --git a/src/core/filters/deskew/ImageView.cpp b/src/core/filters/deskew/ImageView.cpp
index 6a2245529..feb888c27 100644
--- a/src/core/filters/deskew/ImageView.cpp
+++ b/src/core/filters/deskew/ImageView.cpp
@@ -14,7 +14,7 @@
 
 namespace deskew {
 const double ImageView::m_maxRotationDeg = 45.0;
-const double ImageView::m_maxRotationSin = std::sin(m_maxRotationDeg * imageproc::constants::DEG2RAD);
+const double ImageView::m_maxRotationSin = std::sin(m_maxRotationDeg * constants::DEG2RAD);
 const int ImageView::m_cellSize = 20;
 
 ImageView::ImageView(const QImage& image, const QImage& downscaled_image, const ImageTransformation& xform)
@@ -184,7 +184,7 @@ void ImageView::handleMoveRequest(int idx, const QPointF& pos) {
   if (idx == 0) {
     angle_rad = -angle_rad;
   }
-  double angle_deg = angle_rad * imageproc::constants::RAD2DEG;
+  double angle_deg = angle_rad * constants::RAD2DEG;
   angle_deg = qBound(-m_maxRotationDeg, angle_deg, m_maxRotationDeg);
   if (angle_deg == m_xform.postRotation()) {
     return;
diff --git a/src/core/filters/output/DewarpingView.cpp b/src/core/filters/output/DewarpingView.cpp
index 5abd8eb3b..6f0395ca9 100644
--- a/src/core/filters/output/DewarpingView.cpp
+++ b/src/core/filters/output/DewarpingView.cpp
@@ -16,8 +16,6 @@
 #include "spfit/SplineFitter.h"
 
 namespace output {
-using namespace imageproc;
-
 DewarpingView::DewarpingView(const QImage& image,
                              const ImagePixmapUnion& downscaled_image,
                              const QTransform& image_to_virt,
diff --git a/src/core/filters/output/OutputGenerator.cpp b/src/core/filters/output/OutputGenerator.cpp
index 58183305e..6e5703a2d 100644
--- a/src/core/filters/output/OutputGenerator.cpp
+++ b/src/core/filters/output/OutputGenerator.cpp
@@ -1114,7 +1114,8 @@ void movePointToBottomMargin(BinaryImage& bw_image, std::vector<QPointF>& polyli
 }
 
 inline float vertBorderSkewAngle(const QPointF& top, const QPointF& bottom) {
-  return static_cast<float>(std::abs(std::atan((bottom.x() - top.x()) / (bottom.y() - top.y())) * 180.0 / M_PI));
+  return static_cast<float>(
+      std::abs(std::atan((bottom.x() - top.x()) / (bottom.y() - top.y())) * 180.0 / constants::PI));
 }
 
 QImage smoothToGrayscale(const QImage& src, const Dpi& dpi) {
diff --git a/src/core/filters/page_layout/OptionsWidget.cpp b/src/core/filters/page_layout/OptionsWidget.cpp
index abbb0235e..3fc6987d7 100644
--- a/src/core/filters/page_layout/OptionsWidget.cpp
+++ b/src/core/filters/page_layout/OptionsWidget.cpp
@@ -13,7 +13,7 @@
 #include "Settings.h"
 
 using namespace core;
-using namespace imageproc::constants;
+using namespace constants;
 
 namespace page_layout {
 OptionsWidget::OptionsWidget(intrusive_ptr<Settings> settings, const PageSelectionAccessor& page_selection_accessor)
diff --git a/src/foundation/CMakeLists.txt b/src/foundation/CMakeLists.txt
index c7c746885..903ca3950 100644
--- a/src/foundation/CMakeLists.txt
+++ b/src/foundation/CMakeLists.txt
@@ -1,4 +1,5 @@
 set(sources
+    Constants.h Constants.cpp
     NonCopyable.h intrusive_ptr.h ref_countable.h
     AlignedArray.h
     FastQueue.h
diff --git a/src/imageproc/Constants.cpp b/src/foundation/Constants.cpp
similarity index 86%
rename from src/imageproc/Constants.cpp
rename to src/foundation/Constants.cpp
index 66ff1f8a7..aed82db91 100644
--- a/src/imageproc/Constants.cpp
+++ b/src/foundation/Constants.cpp
@@ -3,11 +3,10 @@
 
 #include "Constants.h"
 
-namespace imageproc {
 namespace constants {
 const double SQRT_2 = 1.4142135623730950488016887242097;
 
-const double PI = 3.141592653589793;
+const double PI = 3.141592653589793238462643383279502884;
 
 const double DEG2RAD = PI / 180.0;
 
@@ -21,4 +20,3 @@ const double DPM2DPI = 0.0254;
 
 const double DPI2DPM = 1.0 / DPM2DPI;
 }  // namespace constants
-}  // namespace imageproc
diff --git a/src/imageproc/Constants.h b/src/foundation/Constants.h
similarity index 94%
rename from src/imageproc/Constants.h
rename to src/foundation/Constants.h
index 25e26a9ff..150891878 100644
--- a/src/imageproc/Constants.h
+++ b/src/foundation/Constants.h
@@ -4,7 +4,6 @@
 #ifndef IMAGEPROC_CONSTANTS_H_
 #define IMAGEPROC_CONSTANTS_H_
 
-namespace imageproc {
 namespace constants {
 extern const double PI;
 
@@ -40,5 +39,4 @@ extern const double DPI2DPM;
  */
 extern const double DPM2DPI;
 }  // namespace constants
-}  // namespace imageproc
 #endif
diff --git a/src/imageproc/CMakeLists.txt b/src/imageproc/CMakeLists.txt
index d1731939e..a3c712f90 100644
--- a/src/imageproc/CMakeLists.txt
+++ b/src/imageproc/CMakeLists.txt
@@ -1,5 +1,4 @@
 set(sources
-    Constants.h Constants.cpp
     BinaryImage.cpp BinaryImage.h
     BinaryThreshold.cpp BinaryThreshold.h
     SlicedHistogram.cpp SlicedHistogram.h
diff --git a/src/imageproc/Dpi.cpp b/src/imageproc/Dpi.cpp
index 48c19093a..81d6b8891 100644
--- a/src/imageproc/Dpi.cpp
+++ b/src/imageproc/Dpi.cpp
@@ -7,8 +7,6 @@
 #include <QDomElement>
 #include "Dpm.h"
 
-using namespace imageproc;
-
 Dpi::Dpi() : m_xDpi(0), m_yDpi(0) {}
 
 Dpi::Dpi(int horizontal, int vertical) : m_xDpi(horizontal), m_yDpi(vertical) {}
diff --git a/src/imageproc/Dpm.cpp b/src/imageproc/Dpm.cpp
index 38f40567e..177a55792 100644
--- a/src/imageproc/Dpm.cpp
+++ b/src/imageproc/Dpm.cpp
@@ -6,8 +6,6 @@
 #include "Dpi.h"
 #include <Constants.h>
 
-using namespace imageproc;
-
 Dpm::Dpm(const QSize size) : m_xDpm(size.width()), m_yDpm(size.height()) {}
 
 Dpm::Dpm(const Dpi dpi)