diff --git a/tests/dnn/dnn-layer-mathunary-test.c b/tests/dnn/dnn-layer-mathunary-test.c
index ac26f7445f..540ea4cef5 100644
--- a/tests/dnn/dnn-layer-mathunary-test.c
+++ b/tests/dnn/dnn-layer-mathunary-test.c
@@ -40,6 +40,8 @@ static float get_expected(float f, DNNMathUnaryOperation op)
         return tan(f);
     case DMUO_ASIN:
         return asin(f);
+    case DMUO_ACOS:
+        return acos(f);
     default:
         av_assert0(!"not supported yet");
         return 0.f;
@@ -93,5 +95,7 @@ int main(int agrc, char **argv)
         return 1;
     if (test(DMUO_ASIN))
         return 1;
+    if (test(DMUO_ACOS))
+        return 1;
     return 0;
 }