diff --git a/MagickCore/fx.c b/MagickCore/fx.c
index 169110e..e68260c 100644
--- a/MagickCore/fx.c
+++ b/MagickCore/fx.c
@@ -3632,6 +3632,10 @@
 
   plasma=ClampToQuantum(pixel+noise*GetPseudoRandomValue(random_info)-
     noise/2.0);
+  if (plasma <= 0)
+    return((Quantum) 0);
+  if (plasma > QuantumRange)
+    return(QuantumRange);
   return(plasma);
 }