diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 1f7eab1..b7ebc16 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -33,6 +33,11 @@ jobs:
           CC: gcc
           CXX: g++
 
+      - name: Test
+        run: |
+          source util/ci/script.sh
+          do_functional_test
+
   clang:
     runs-on: ubuntu-20.04
     steps:
@@ -49,3 +54,8 @@ jobs:
         env:
           CC: clang
           CXX: clang++
+
+      - name: Test
+        run: |
+          source util/ci/script.sh
+          do_functional_test
diff --git a/util/ci/script.sh b/util/ci/script.sh
index c27c98f..3d8d35b 100755
--- a/util/ci/script.sh
+++ b/util/ci/script.sh
@@ -13,3 +13,15 @@ run_build() {
 
 	make -j2
 }
+
+do_functional_test() {
+	mkdir testmap
+	echo "backend = sqlite3" >testmap/world.mt
+	sqlite3 testmap/map.sqlite <<END
+CREATE TABLE blocks(pos INT,data BLOB);
+INSERT INTO blocks(pos, data) VALUES(0, x'$(cat util/ci/test_block)');
+END
+
+	./minetestmapper --noemptyimage -i ./testmap -o map.png
+	file map.png
+}
diff --git a/util/ci/test_block b/util/ci/test_block
new file mode 100644
index 0000000..359f6f6
--- /dev/null
+++ b/util/ci/test_block
@@ -0,0 +1 @@
+1b00ffff020278daedd4c1090000080331dd7f691710faf12589235cb12ae870fca6bffefaebafbffefaebafbffefaebbff7b708fdf1ffd11ffdd11ffdd11ffd01000000000000003836d59f010578da63000000010001000000ffffffff000002000000036169720001000d64656661756c743a73746f6e650a0000