diff --git a/progs/fpglsl/fp-tri.c b/progs/fpglsl/fp-tri.c
index c9b08fbbad7..8af09845dd8 100644
--- a/progs/fpglsl/fp-tri.c
+++ b/progs/fpglsl/fp-tri.c
@@ -128,6 +128,11 @@ static void setup_uniforms()
 
    }
 
+   {
+      GLint loci = glGetUniformLocationARB(program, "KernelSizeInt");
+      if (loci >= 0)
+         glUniform1i(loci, 4);
+   }
    {
       GLint loc1f = glGetUniformLocationARB(program, "KernelValue1f");
       GLint loc2f = glGetUniformLocationARB(program, "KernelValue2f");