diff --git a/tests/dnn/dnn-layer-mathunary-test.c b/tests/dnn/dnn-layer-mathunary-test.c
index ed42198195..23e1766ad0 100644
--- a/tests/dnn/dnn-layer-mathunary-test.c
+++ b/tests/dnn/dnn-layer-mathunary-test.c
@@ -34,6 +34,8 @@ static float get_expected(float f, DNNMathUnaryOperation op)
         return (f >= 0) ? f : -f;
     case DMUO_SIN:
         return sin(f);
+    case DMUO_COS:
+        return cos(f);
     default:
         av_assert0(!"not supported yet");
         return 0.f;
@@ -81,5 +83,7 @@ int main(int agrc, char **argv)
         return 1;
     if (test(DMUO_SIN))
         return 1;
+    if (test(DMUO_COS))
+        return 1;
     return 0;
 }