diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 5958515b1..168163ee2 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -339,7 +339,7 @@ jobs:
       fail-fast: false
       matrix:
         build_type: [Release, Debug]
-        llvm_version: [16,17]
+        llvm_version: [16]
 
     steps:
       - uses: actions/checkout@v4
@@ -424,7 +424,7 @@ jobs:
           python3 src/tester.py ../build/c3c test_suite/
 
       - name: bundle_output
-        if: matrix.llvm_version == 17
+        if: matrix.llvm_version == 16
         run: |
           mkdir linux
           cp -r lib linux
@@ -433,7 +433,7 @@ jobs:
           tar czf c3-ubuntu-20-${{matrix.build_type}}.tar.gz linux
 
       - name: upload artifacts
-        if: matrix.llvm_version == 17
+        if: matrix.llvm_version == 16
         uses: actions/upload-artifact@v3
         with:
           name: c3-ubuntu-20-${{matrix.build_type}}
diff --git a/test/test_suite/vector/vector_lowering_regression1.c3t b/test/test_suite/vector/vector_lowering_regression1.c3t
new file mode 100644
index 000000000..e44d51573
--- /dev/null
+++ b/test/test_suite/vector/vector_lowering_regression1.c3t
@@ -0,0 +1,12 @@
+// #target: linux-x64
+module test;
+union Vec4f @export @align(16) {
+  struct { float x,y,z,w; }
+  float[<4>] v;
+}
+
+extern fn void foo(Vec4f) @extern("foo");
+
+/* #expect: test.ll
+
+declare void @foo(double, double) #0
\ No newline at end of file