diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..0b9c497
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,31 @@
+name: Test
+on:
+  push:
+
+jobs:
+  build_and_test:
+    name: "Build and Test"
+    strategy:
+      fail-fast: false
+      matrix:
+        runner: [ubuntu-24.04, macos-15]
+    runs-on: ${{ matrix.runner }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: true
+      # No need to install dependencies — only Ninja and CMake are needed,
+      # slang CMakeLists.txt fetch the rest.
+      #
+      #    https://github.com/actions/runner-images
+      - name: Build
+        run: |
+          rm -rf ./build
+          mkdir -p ./build
+          cd ./build
+          cmake -G Ninja ..
+          ninja
+      - name: Test
+        run: |
+          cd ./build
+          ctest
diff --git a/src/driver.cc b/src/driver.cc
index aab6540..b6d6902 100644
--- a/src/driver.cc
+++ b/src/driver.cc
@@ -429,28 +429,25 @@ void prunefl::Driver::write_output_flags() const {
 
 	// defines
 	for (auto &define : options.defines) {
-		output_flags.insert(std::string("+define+") + define);
+		output_flags.insert(fmt::format("+define+{}", define));
 	}
 
 	// include search directories
 	for (auto &file : result_includes) {
 		output_flags.insert(
-			std::string("+incdir+") + file.parent_path().string()
+			fmt::format("+incdir+{}", file.parent_path().string())
 		);
 	}
 
 	// module search directories
 	for (auto &dir : sourceLoader.getSearchDirectories()) {
-		output_flags.insert(std::string("-y ") + dir.string());
+		output_flags.insert(fmt::format("-y {}", dir.string()));
 	}
 
 	// module search extensions
-	if (verific_compat_mode) {
-		output_flags.insert(std::string("+libext+"));
-	} else {
-		for (auto &ext : sourceLoader.getSearchExtensions()) {
-			output_flags.insert(std::string("-Y ") + ext.string());
-		}
+	std::string_view libext_pfx = verific_compat_mode ? "+libext+" : "-Y ";
+	for (auto &ext : sourceLoader.getSearchExtensions()) {
+		output_flags.insert(fmt::format("{}{}", libext_pfx, ext.string()));
 	}
 
 	// library files
@@ -465,14 +462,14 @@ void prunefl::Driver::write_output_flags() const {
 	}
 
 	// input command file
-	if (verific_compat_mode) {
-		// verific is single-unit by default, so -C doesn't matter
-		output_flags.insert(fmt::format("-f {}", fs::absolute(*output).c_str())
-		);
-	} else {
-		output_flags.insert(fmt::format("-C {}", fs::absolute(*output).c_str())
-		);
-	}
+	std::string_view cmdfile_pfx =
+		verific_compat_mode
+			? "-f " // verific is single-unit by default, so -C doesn't matter
+			: "-C ";
+
+	output_flags.insert(
+		fmt::format("{}{}", cmdfile_pfx, fs::absolute(*output).c_str())
+	);
 
 	std::string out_string;
 	for (auto &flag : output_flags) {
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 4382a61..87827b1 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -8,6 +8,7 @@ set(ALL_TESTS
   test_cli_define
   test_libmap
   test_timescales
+  test_no_list
 )
 
 foreach(test_name ${ALL_TESTS})
diff --git a/test/run_test b/test/run_test
index 8331414..80650b7 100755
--- a/test/run_test
+++ b/test/run_test
@@ -21,10 +21,30 @@ assert len(unused & result) == 0
 HERE
 }
 
-$prunefl -f list.f --top top_module \
+rm -f $bindir/$test.cache.json
+
+input_file="-f list.f"
+if ! test -f list.f; then
+  input_file=test.v
+fi
+
+$prunefl $input_file --top top_module \
+  --verific-compat --ignore-unknown-modules\
   --output-flags-to $bindir/$test.flags.f \
-  --output $bindir/$test.f
+  --output $bindir/$test.f \
+  --cache-to $bindir/$test.cache.json
 
 verify_unused ./unused.txt $bindir/$test.flags.f
 
-$slang_hier -F $bindir/$test.flags.f --top top_module --compat all --timescale=1ns/1ns
+$slang_hier --single-unit -F $bindir/$test.flags.f --top top_module --compat all --timescale=1ns/1ns
+
+# test loading from cache
+$prunefl $input_file --top top_module \
+  --verific-compat --ignore-unknown-modules\
+  --output-flags-to $bindir/$test.flags.cached.f \
+  --output $bindir/$test.cached.f \
+  --cache-to $bindir/$test.cache.json
+
+# only difference should be that it points to .cached.f instead of .f
+cat $bindir/$test.flags.cached.f | sed 's/.cached.f/.f/' | cmp $bindir/$test.flags.f - 
+cmp $bindir/$test.f $bindir/$test.cached.f
diff --git a/test/test_no_list/test.v b/test/test_no_list/test.v
new file mode 100644
index 0000000..e502f11
--- /dev/null
+++ b/test/test_no_list/test.v
@@ -0,0 +1,11 @@
+module top_module
+#(
+    parameter DEC_WIDTH = 8,
+    parameter ENC_WIDTH = 3
+)
+(
+    input  wire [ENC_WIDTH-1:0] in_enc_nnn,
+    output wire [DEC_WIDTH-1:0] out_dec_nnn
+);
+  assign out_dec_nnn = DEC_WIDTH'(1'b1 << in_enc_nnn);
+endmodule