diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 7227a2f1..eae05af6 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -11,29 +11,48 @@ env:
   INTTEST_URL: https://github.com/SacBase/IntegrationTests.git
 
 jobs:
-  build-ubuntu24:
-    runs-on: ubuntu-24.04
+  build-ubuntu26:
+    runs-on: ubuntu-26.04
+    container:
+      image: nvidia/cuda:13.3.1-devel-ubuntu26.04
     steps:
+    - name: Install dependencies
+      run: |
+        apt-get update
+        apt-get install --no-install-recommends -y \
+          git \
+          cmake \
+          python3 \
+          ninja-build \
+          ca-certificates \
+          libhwloc-dev \
+          uuid-runtime \
+          uuid-dev \
+          xsltproc \
+          bison \
+          flex \
+          m4
     - name: Get HEAD and submodules
       uses: actions/checkout@v6
       with:
         fetch-depth: 0
         submodules: 'recursive'
-    - name: Install dependencies
-      run: |
-        sudo apt update
-        sudo apt install xsltproc -y
     - name: Install sac2c
       run: |
         git clone --single-branch --recursive ${SAC2C_URL} sac2c
         cd sac2c
-        cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=RELEASE
+        cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=RELEASE -DCUDA=ON
         cmake --build build -j4
         ln -s $PWD/build/sac2c_p /usr/local/bin/sac2c
         sac2c -V
+    - name: Configure Git
+      run: git config --global --add safe.directory "$GITHUB_WORKSPACE"
     - name: Configure build system
       run: |
-        cmake -S . -B build -G Ninja
+        cmake -S . -B build -G Ninja \
+          -DTARGETS="seq;seq_checks;mt_pth;cuda" \
+          -DBUILD_EXT=ON \
+          -DLINKSETSIZE=200
     - name: Build
       shell: bash
       run: |
@@ -54,15 +73,15 @@ jobs:
   build-macos-arm:
     runs-on: macos-latest
     steps:
+    - name: Install dependencies
+      run: |
+        brew update
+        brew install libxslt
     - name: Get HEAD and submodules
       uses: actions/checkout@v6
       with:
         fetch-depth: 0
         submodules: 'recursive'
-    - name: Install dependencies
-      run: |
-        brew update
-        brew install libxslt
     - name: Set XCode version
       uses: maxim-lobanov/setup-xcode@v1
       with:
@@ -77,7 +96,9 @@ jobs:
         sac2c -V
     - name: Configure build system
       run: |
-        cmake -S . -B build -G Ninja
+        cmake -S . -B build -G Ninja \
+          -DTARGETS="seq;seq_checks;mt_pth" \
+          -DBUILD_EXT=ON
     - name: Build
       shell: bash
       run: |
diff --git a/src/structures/String.sac b/src/structures/String.sac
index 1f84cf4c..0e22d6ad 100644
--- a/src/structures/String.sac
+++ b/src/structures/String.sac
@@ -10,8 +10,11 @@ module String;
 
 export all except { indent };
 
+// Using `pragma ctype` leads to issues when compiling for CUDA. CUDA compiles
+// generated code as C++, where using `ctype` introduces an implicit cast from
+// void* to char*, which is not allowed in C++.
 external typedef string;
-    #pragma ctype "char*"
+    // #pragma ctype "char*"
     #pragma copyfun "copy_string"
     #pragma freefun "free_string"
     #pragma linkobj "src/String/Str.o"