diff --git a/.github/workflows/build_and_test_compiler_zoo.yml b/.github/workflows/build_and_test_compiler_zoo.yml
index be32d71..6471de3 100644
--- a/.github/workflows/build_and_test_compiler_zoo.yml
+++ b/.github/workflows/build_and_test_compiler_zoo.yml
@@ -14,11 +14,26 @@ jobs:
         image: dbwy/chemistry
     strategy:
       matrix:
-        compiler: [ {suite: gnu, version: 12}, {suite: llvm, version: 14} ]
+        compiler:
+          - {suite: gnu,  version: 12}
+          - {suite: llvm, version: 14}
+          - {suite: llvm, version: 19}
+          - {suite: llvm, version: 21}
 
     steps:
     - uses: actions/checkout@v3
 
+    - name: Install LLVM toolchain
+      if: ${{ matrix.compiler.suite == 'llvm' }}
+      shell: bash
+      run: |
+        set -euo pipefail
+        apt-get update
+        apt-get install -y wget gnupg lsb-release software-properties-common
+        wget https://apt.llvm.org/llvm.sh
+        chmod +x llvm.sh
+        ./llvm.sh ${{ matrix.compiler.version }} -y
+
     - name: Setup Compiler 
       shell: bash
       run: $GITHUB_WORKSPACE/.github/workflows/scripts/compiler_setup.sh 
diff --git a/.github/workflows/scripts/compiler_setup.sh b/.github/workflows/scripts/compiler_setup.sh
index 2d6fae0..467ed0f 100755
--- a/.github/workflows/scripts/compiler_setup.sh
+++ b/.github/workflows/scripts/compiler_setup.sh
@@ -1,10 +1,13 @@
-#/bin/bash
+#!/bin/bash
 
 export CSUITE=$1
 export CVER=$2
 
 if [[ "${CSUITE}" == "llvm" ]]
 then
+  # register the specific clang version as an alternative (needed once per version)
+  update-alternatives --install /usr/bin/clang   clang   /usr/bin/clang-${CVER}   50
+  update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-${CVER} 50
   update-alternatives --set clang   /usr/bin/clang-${CVER}
   update-alternatives --set clang++ /usr/bin/clang++-${CVER}
   update-alternatives --install /usr/bin/cc  cc  /usr/bin/clang   30
@@ -20,3 +23,6 @@ else
   exit 125
 fi
 
+echo "Selected compilers:"
+echo "  cc  -> $(command -v cc)  | $(cc --version | head -1)"
+echo "  c++ -> $(command -v c++) | $(c++ --version | head -1)"
diff --git a/include/integratorxx/quadratures/radial/radial_transform.hpp b/include/integratorxx/quadratures/radial/radial_transform.hpp
index a319a49..89257ef 100644
--- a/include/integratorxx/quadratures/radial/radial_transform.hpp
+++ b/include/integratorxx/quadratures/radial/radial_transform.hpp
@@ -32,8 +32,13 @@ struct RadialTransformQuadrature :
   using point_container  = typename base_type::point_container;
   using weight_container = typename base_type::weight_container;
 
-  RadialTransformQuadrature(const RadialTraitsType& traits = RadialTraitsType()) :
-    base_type(traits) { }
+  RadialTransformQuadrature(const RadialTraitsType& traits)
+    : base_type(traits) {}
+
+  template<class T = RadialTraitsType,
+           class = std::enable_if_t<std::is_default_constructible<T>::value>>
+  RadialTransformQuadrature() : base_type(T{}) {}
+
   RadialTransformQuadrature(const RadialTraits& traits) :
     RadialTransformQuadrature(radial_traits_cast<RadialTraitsType>(traits)) { }