diff --git a/cuburn/code/output.py b/cuburn/code/output.py
index 7a3ab7f..636e013 100644
--- a/cuburn/code/output.py
+++ b/cuburn/code/output.py
@@ -205,9 +205,9 @@ __global__ void f32_to_yuv444p12(
     mwc_st rctx = rctxs[rb_incr(rb->head, tid)];
 
     float4 in = src[isrc];
-    in.x = fminf(1.0f, in.x);
-    in.y = fminf(1.0f, in.y);
-    in.z = fminf(1.0f, in.z);
+    in.x = fminf(1.0f, fmaxf(0.0f, in.x));
+    in.y = fminf(1.0f, fmaxf(0.0f, in.y));
+    in.z = fminf(1.0f, fmaxf(0.0f, in.z));
     ushort3 out = make_ushort3(
         dclampf(rctx, 4095.0f, 0.299f      * in.x + 0.587f     * in.y + 0.114f     * in.z),
         dclampf(rctx, 4095.0f, -0.168736f  * in.x - 0.331264f  * in.y + 0.5f       * in.z + 0.5f),