diff --git a/.github/workflows/test_library.yaml b/.github/workflows/test_library.yaml
index 9a8e496..fae83f9 100644
--- a/.github/workflows/test_library.yaml
+++ b/.github/workflows/test_library.yaml
@@ -7,7 +7,7 @@ concurrency:
 on: [push, pull_request]
 
 jobs:
-  Tests-Viewshed-library:
+  Tests-Viewshed-library-linux:
     runs-on: ubuntu-26.04
 
     env:
@@ -33,8 +33,45 @@ jobs:
 
       - uses: actions/checkout@v6
         with:
-          # Repository name with owner. For example, actions/checkout
-          # Default: ${{ github.repository }}
+          repository: "JanCaha/cpp-simplerasters"
+          path: "cpp-simplerasters"
+
+      - name: Install simplerasters
+        run: |
+          cd cpp-simplerasters
+          sudo cmake --workflow --preset workflow-release-install
+          cd ..
+          sudo rm -rf cpp-simplerasters
+
+      - name: Checkout
+        uses: actions/checkout@v6
+        with:
+          submodules: true
+
+      - name: Test
+        run: |
+          cmake --workflow --preset workflow-debug-tests
+
+      - name: Install
+        run: |
+          sudo cmake --workflow --preset workflow-release-install
+
+  Tests-Viewshed-library-macos:
+    runs-on: macos-latest
+
+    env:
+      QT_QPA_PLATFORM: "offscreen"
+      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      CMAKE_PREFIX_PATH: "/opt/homebrew/opt/qt@6"
+
+    steps:
+      - name: Install dependencies
+        run: |
+          brew update
+          brew install ninja doxygen googletest gdal qt@6
+
+      - uses: actions/checkout@v6
+        with:
           repository: "JanCaha/cpp-simplerasters"
           path: "cpp-simplerasters"
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 29c0a6c..b10c606 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.24.0)
 
 # Project Information
-project(viewshed VERSION 6.0.0 DESCRIPTION "C++ Viewshed library based on GDAL and Qt" LANGUAGES CXX)
+project(viewshed VERSION 6.1.0 DESCRIPTION "C++ Viewshed library based on GDAL and Qt" LANGUAGES CXX)
 
 # Library Name
 SET(LIBRARY_NAME "Viewshed")
diff --git a/CMakePresets.json b/CMakePresets.json
index 00ffb25..7d7bb1b 100644
--- a/CMakePresets.json
+++ b/CMakePresets.json
@@ -29,7 +29,7 @@
             "cacheVariables": {
                 "CMAKE_BUILD_TYPE": "Release",
                 "BUILD_TESTS": "OFF",
-                "CMAKE_INSTALL_PREFIX": "/usr",
+                "CMAKE_INSTALL_PREFIX": "/usr/local",
                 "BUILD_DOCUMENTATION": "ON"
             }
         }
diff --git a/README.md b/README.md
index 00a842f..e83779e 100644
--- a/README.md
+++ b/README.md
@@ -107,8 +107,8 @@ If you use the library, please cite it accordingly:
   author  = {Jan Caha},
   title   = {viewshed ({C++ Viewshed library based on GDAL and Qt})},
   year    = {2026}
-  date    = {2026-07-05}
-  version = {6.0.0}
+  date    = {2026-07-06}
+  version = {6.1.0}
   url     = {https://github.com/JanCaha/cpp-viewshed-library},
 }
 ```
diff --git a/conda/meta.yaml b/conda/meta.yaml
index e5f022d..61b7b69 100644
--- a/conda/meta.yaml
+++ b/conda/meta.yaml
@@ -1,6 +1,6 @@
 package:
   name: libviewshed
-  version: "6.0.0"
+  version: "6.1.0"
 
 source:
   path: ..
diff --git a/scripts/build_docker.sh b/scripts/build_docker.sh
deleted file mode 100755
index 94cad64..0000000
--- a/scripts/build_docker.sh
+++ /dev/null
@@ -1,29 +0,0 @@
-set -u
-set -e
-
-PWD=`pwd`
-
-cd docker
-
-IMAGE_NAME=viewshed
-
-DOCKER_IMAGE_NAME=cahik/viewshed:latest
-
-docker build -t $IMAGE_NAME .
-
-docker tag $IMAGE_NAME $DOCKER_IMAGE_NAME
-
-docker login --username cahik
-
-docker push $DOCKER_IMAGE_NAME
-
-
-# DOCKER_IMAGE_NAME=cahik/viewshed:latest-python
-
-# docker build -t $IMAGE_NAME -f viewshed_install_from_ppa.dockerfile .
-
-# docker tag $IMAGE_NAME $DOCKER_IMAGE_NAME
-
-# docker login --username cahik
-
-# docker push $DOCKER_IMAGE_NAME
\ No newline at end of file
diff --git a/scripts/install.sh b/scripts/install.sh
index a73c2fd..f801340 100755
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -1,2 +1,6 @@
+#!/bin/bash
+
+set -e
+
 # install
 sudo cmake --workflow --preset workflow-release-install
diff --git a/scripts/release.sh b/scripts/release.sh
deleted file mode 100755
index 27c25b1..0000000
--- a/scripts/release.sh
+++ /dev/null
@@ -1,30 +0,0 @@
-FOLDER=cpp-viewshed-library
-PACKAGE=viewshed
-VERSION=$(grep "project("  CMakeLists.txt | grep -E -o -e "[0-9\.]+" | head -n 1)
-DEBIAN_VERSION=$(grep "viewshed (" debian/changelog | grep -E -o -e "[0-9\.-]+" | head -n 1)
-
-cmake \
-    -S. \
-    -B build \
-    -G Ninja \
-    -DCMAKE_CXX_COMPILER=clang++-13 \
-    -D CMAKE_INSTALL_PREFIX=debian/tmp/ \
-    -D CMAKE_BUILD_TYPE=Release \
-    -D BUILD_TESTS:bool=off \
-    -D CMAKE_INSTALL_PREFIX=/usr
-
-cmake --build build --config Release --target all
-# cmake --build build --config Release --target install
-
-cd ..
-dir
-tar -acf "${PACKAGE}"_"${DEBIAN_VERSION}".orig.tar.gz $FOLDER
-ls -l
-
-cd $FOLDER
-
-debuild -S -sa -d
-
-cd ..
-
-dput ppa:jancaha/gis-tools "${PACKAGE}"_"${DEBIAN_VERSION}"_source.changes
\ No newline at end of file
diff --git a/scripts/release_to_ppa.sh b/scripts/release_to_ppa.sh
deleted file mode 100755
index a378b9e..0000000
--- a/scripts/release_to_ppa.sh
+++ /dev/null
@@ -1,20 +0,0 @@
-#!bin/bash
-
-set -u
-set -e
-
-PWD=`pwd`
-
-FOLDER=cpp-viewshed-library
-PACKAGE=viewshed
-VERSION=$(grep "project("  CMakeLists.txt | grep -E -o -e "[0-9\.]+" | head -n 1)
-DEBIAN_VERSION=$(grep "viewshed (" debian/changelog | grep -E -o -e "[0-9\.-]+" | head -n 1)
-
-rm -rf build
-cd ..
-tar -acf "${PACKAGE}"_"${VERSION}".orig.tar.gz $FOLDER
-cd $FOLDER
-debuild -S -sa -d
-cd ..
-dput ppa:jancaha/gis-tools "${PACKAGE}"_"${DEBIAN_VERSION}"_source.changes
-# rm $PACKAGE*
\ No newline at end of file
diff --git a/scripts/test.sh b/scripts/test.sh
index 7e05e12..bd16fd3 100755
--- a/scripts/test.sh
+++ b/scripts/test.sh
@@ -1 +1,5 @@
+#!/bin/bash
+
+set -e
+
 cmake --workflow --preset workflow-debug-tests
diff --git a/scripts/uninstall.sh b/scripts/uninstall.sh
index 6773ec1..20ac283 100755
--- a/scripts/uninstall.sh
+++ b/scripts/uninstall.sh
@@ -1,4 +1,8 @@
-sudo rm /usr/local/bin/inverseviewshed /usr/local/bin/viewshed /usr/local/bin/viewshedcalculator /usr/local/bin/losextractor
-sudo rm /usr/local/lib/libviewshed.so /usr/local/lib/libviewshed.so.* /usr/local/lib/libviewshedwidgets.so /usr/local/lib/libviewshedwidgets.so.*
+#!/bin/bash
+
+set -e
+
+sudo rm -f /usr/local/bin/inverseviewshed /usr/local/bin/viewshed /usr/local/bin/viewshedcalculator /usr/local/bin/losextractor
+sudo rm -f /usr/local/lib/libviewshed.so /usr/local/lib/libviewshed.so.* /usr/local/lib/libviewshedwidgets.so /usr/local/lib/libviewshedwidgets.so.*
 sudo rm -rf /usr/local/include/Viewshed
-sudo rm -rf /usr/local/lib/cmake/Viewshed
\ No newline at end of file
+sudo rm -rf /usr/local/lib/cmake/Viewshed
diff --git a/src/library/structures/cellevent.cpp b/src/library/structures/cellevent.cpp
index 36ba9b8..b62bdd8 100644
--- a/src/library/structures/cellevent.cpp
+++ b/src/library/structures/cellevent.cpp
@@ -34,32 +34,35 @@ bool CellEvent::operator==( const CellEvent &other ) const
            mBehindTargetForInverseLoS == other.mBehindTargetForInverseLoS;
 }
 
-bool CellEvent::operator<( const CellEvent &other ) const
+// order of events at equal angle: EXIT first, then CENTER, then ENTER
+static int eventTypeSortRank( CellEventPositionType eventType )
 {
-
-    if ( mRow == other.mRow && mCol == other.mCol && mEventType == other.mEventType && mBehindTargetForInverseLoS &&
-         other.mBehindTargetForInverseLoS )
-        return false;
-
-    if ( mAngle > other.mAngle )
+    switch ( eventType )
     {
-        return false;
+        case CellEventPositionType::EXIT:
+            return 0;
+        case CellEventPositionType::CENTER:
+            return 1;
+        default:
+            return 2;
     }
-    else if ( mAngle < other.mAngle )
+}
+
+// must be a strict weak ordering, otherwise std::sort is undefined behaviour
+// (the previous version returned true for `a<a` on EXIT events with equal angles,
+// which made std::sort in libc++ on macOS read out of bounds and segfault)
+bool CellEvent::operator<( const CellEvent &other ) const
+{
+    if ( mAngle < other.mAngle )
     {
         return true;
     }
-    else
+
+    if ( other.mAngle < mAngle )
     {
-        /*a.angle == b.angle */
-        if ( mEventType == CellEventPositionType::EXIT )
-            return true;
-        if ( other.mEventType == CellEventPositionType::EXIT )
-            return false;
-        if ( mEventType == CellEventPositionType::ENTER )
-            return false;
-        if ( other.mEventType == CellEventPositionType::ENTER )
-            return true;
         return false;
     }
+
+    /*a.angle == b.angle */
+    return eventTypeSortRank( mEventType ) < eventTypeSortRank( other.mEventType );
 }
\ No newline at end of file
diff --git a/tests/testcellevent.cpp b/tests/testcellevent.cpp
index ae2f05c..e2e39f9 100644
--- a/tests/testcellevent.cpp
+++ b/tests/testcellevent.cpp
@@ -112,6 +112,89 @@ TEST_F( CellEventTest, testCellEventCreation2 )
     ASSERT_NEAR( c.mAngle, 3.926990, 0.000001 );
 }
 
+CellEvent makeEvent( CellEventPositionType type, int row, int col, double angle )
+{
+    double elevs[3] = { 1000, 1000, 1000 };
+    return CellEvent( type, row, col, 1.0, angle, elevs );
+}
+
+// operator< is used by std::sort in AbstractViewshed::sortEventList and must therefore
+// be a strict weak ordering, otherwise the sort is undefined behaviour
+// (it segfaults with libc++ on macOS)
+
+TEST( CellEventComparison, irreflexivity )
+{
+    // a < a must always be false
+    CellEvent enter = makeEvent( CellEventPositionType::ENTER, 5, 5, 0.785398 );
+    CellEvent center = makeEvent( CellEventPositionType::CENTER, 5, 5, 0.785398 );
+    CellEvent exit = makeEvent( CellEventPositionType::EXIT, 5, 5, 0.785398 );
+
+    ASSERT_FALSE( enter < enter );
+    ASSERT_FALSE( center < center );
+    ASSERT_FALSE( exit < exit );
+}
+
+TEST( CellEventComparison, asymmetry )
+{
+    // a < b and b < a must never both be true
+    // events of the same type with equal angles exist for cells on the same ray from the viewpoint
+    CellEvent exitA = makeEvent( CellEventPositionType::EXIT, 5, 5, 0.785398 );
+    CellEvent exitB = makeEvent( CellEventPositionType::EXIT, 10, 10, 0.785398 );
+
+    ASSERT_FALSE( ( exitA < exitB ) && ( exitB < exitA ) );
+
+    CellEvent enterA = makeEvent( CellEventPositionType::ENTER, 5, 5, 0.785398 );
+    CellEvent enterB = makeEvent( CellEventPositionType::ENTER, 10, 10, 0.785398 );
+
+    ASSERT_FALSE( ( enterA < enterB ) && ( enterB < enterA ) );
+
+    CellEvent centerA = makeEvent( CellEventPositionType::CENTER, 5, 5, 0.785398 );
+    CellEvent centerB = makeEvent( CellEventPositionType::CENTER, 10, 10, 0.785398 );
+
+    ASSERT_FALSE( ( centerA < centerB ) && ( centerB < centerA ) );
+}
+
+TEST( CellEventComparison, behindTargetDuplicatesAreEquivalent )
+{
+    // InverseViewshed creates at most one behind-target event per cell and type,
+    // so two events matching on row, col and type always share the same angle
+    // and neither may compare less than the other
+    CellEvent a = makeEvent( CellEventPositionType::EXIT, 5, 5, 0.785398 );
+    a.mBehindTargetForInverseLoS = true;
+
+    CellEvent b = makeEvent( CellEventPositionType::EXIT, 5, 5, 0.785398 );
+    b.mBehindTargetForInverseLoS = true;
+
+    ASSERT_FALSE( a < b );
+    ASSERT_FALSE( b < a );
+}
+
+TEST( CellEventComparison, orderedByAngle )
+{
+    CellEvent smallerAngle = makeEvent( CellEventPositionType::ENTER, 5, 5, 0.5 );
+    CellEvent largerAngle = makeEvent( CellEventPositionType::EXIT, 10, 10, 1.5 );
+
+    ASSERT_TRUE( smallerAngle < largerAngle );
+    ASSERT_FALSE( largerAngle < smallerAngle );
+}
+
+TEST( CellEventComparison, equalAngleOrderedByEventType )
+{
+    // at equal angle the order is EXIT, CENTER, ENTER
+    CellEvent enter = makeEvent( CellEventPositionType::ENTER, 5, 5, 0.785398 );
+    CellEvent center = makeEvent( CellEventPositionType::CENTER, 10, 10, 0.785398 );
+    CellEvent exit = makeEvent( CellEventPositionType::EXIT, 15, 15, 0.785398 );
+
+    ASSERT_TRUE( exit < center );
+    ASSERT_FALSE( center < exit );
+
+    ASSERT_TRUE( center < enter );
+    ASSERT_FALSE( enter < center );
+
+    ASSERT_TRUE( exit < enter );
+    ASSERT_FALSE( enter < exit );
+}
+
 int main( int argc, char **argv )
 {
     testing::InitGoogleTest( &argc, argv );