Use pixel accessor, GetPixelAlpha()
diff --git a/MagickCore/module.c b/MagickCore/module.c
index 78ccd8a..60650c9 100644
--- a/MagickCore/module.c
+++ b/MagickCore/module.c
@@ -399,6 +399,8 @@
 MagickExport char **GetModuleList(const char *pattern,
   const MagickModuleType type,size_t *number_modules,ExceptionInfo *exception)
 {
+#define MaxModules  511
+
   char
     **modules,
     filename[MagickPathExtent],
@@ -445,7 +447,7 @@
   if (status == MagickFalse)
     return((char **) NULL);
   GetPathComponent(module_path,HeadPath,path);
-  max_entries=255;
+  max_entries=MaxModules;
   modules=(char **) AcquireQuantumMemory((size_t) max_entries+1UL,
     sizeof(*modules));
   if (modules == (char **) NULL)