diff -urNp a/editor/ppmfade b/editor/ppmfade
--- a/editor/ppmfade	2025-02-04 10:47:27.812451607 +0100
+++ b/editor/ppmfade	2025-02-04 10:52:14.233336029 +0100
@@ -99,6 +99,9 @@ sub commandLineArgs() {
             $mode = 'BLOCK';
         } elsif ($arg eq "-mix") {
             $mode = 'MIX';
+        } elsif ($arg eq "-help" || $arg eq "--help" || $arg eq "-h") {
+            print STDERR ("ppmfade: Use 'man ppmfade' for help.\n");
+            exit 1;
         } else {
             if (substr($arg, 0, 1) eq '-') {
                    print STDERR ("Unknown option '$arg'.  " .
@@ -109,13 +112,13 @@ sub commandLineArgs() {
                 print STDERR ("There are no non-option arguments possible.  " .
                               "You specified '$arg'\n");
             }
-            exit 100;
+            exit 1;
         }
     }
 
     if (!defined($firstFileNm) && !defined($lastFileNm)) {
         print STDERR ("You must specify -f or -l (or both)\n");
-        exit 90;
+        exit 1
     }
 
     if (!defined($mode)) {
@@ -142,7 +145,7 @@ sub imageDimensions($$) {
         } else {
             print STDERR
                 ("Unrecognized results from pnmfile on $firstFileNm.\n");
-            exit(50);
+            exit(1);
         }
     } else {
         # $lastFileNm is defined
@@ -151,7 +154,7 @@ sub imageDimensions($$) {
         } else {
             print STDERR
                 ("Unrecognized results from pnmfile on $firstFileNm.\n");
-            exit(50);
+            exit(1);
         }
     }
     return $width, $height;
@@ -436,12 +439,12 @@ my ($mode, $firstFileNm, $lastFileNm, $b
 
 if (defined($firstFileNm) && !-e($firstFileNm)) {
     print STDERR ("First file '$firstFileNm' does not exist\n");
-    exit 20;
+    exit 1;
 }
 
 if (defined($lastFileNm) && !-e($lastFileNm)) {
     print STDERR ("Last file '$lastFileNm' does not exist\n");
-    exit 20;
+    exit 1;
 }
 
 my ($width, $height) = imageDimensions($firstFileNm, $lastFileNm);