diff --git a/tools/ci.sh b/tools/ci.sh
index 49fbb73261a..69d8d6a32d9 100644
--- a/tools/ci.sh
+++ b/tools/ci.sh
@@ -132,6 +132,13 @@ function set_capabilities {
 }
 
 function unit_tests {
+    # tcc does not support multi-threading
+    # because it does not have atomic intrinsics
+    if [[ "${CC}" == "tcc" ]] then
+        MULTITHREADING=0
+    else
+        MULTITHREADING=100
+    fi
     mkdir -p build; cd build; rm -rf *
     cmake -DCMAKE_BUILD_TYPE=Debug \
           -DUA_BUILD_EXAMPLES=ON \
@@ -144,6 +151,7 @@ function unit_tests {
           -DUA_ENABLE_MQTT=ON \
           -DUA_ENABLE_PUBSUB_INFORMATIONMODEL=ON \
           -DUA_FORCE_WERROR=ON \
+          -DUA_MULTITHREADING=${MULTITHREADING} \
           ..
     make ${MAKEOPTS}
     set_capabilities