diff --git a/lib/dumpvar.pl b/lib/dumpvar.pl
index b2f3798c43cc..47d7425be2fc 100644
--- a/lib/dumpvar.pl
+++ b/lib/dumpvar.pl
@@ -477,26 +477,32 @@ sub main::dumpvar {
     $package .= "::" unless $package =~ /::$/;
     *stab = *{"main::"};
     while ($package =~ /(\w+?::)/g){
-      *stab = $ {stab}{$1};
+        *stab = $ {stab}{$1};
     }
     local $TotalStrings = 0;
     local $Strings = 0;
     local $CompleteTotal = 0;
-    while (($key,$val) = each(%stab)) {
-      return if $DB::signal;
-      next if @vars && !grep( matchvar($key, $_), @vars );
-      if ($usageOnly) {
-	globUsage(\$val, $key)
-	  if ($package ne 'dumpvar' or $key ne 'stab')
-	     and ref(\$val) eq 'GLOB';
-      } else {
-       dumpglob(0,$key, $val, 0, $m);
-      }
+    for my $key (keys %stab) {
+        my $val = $stab{$key};
+        return if $DB::signal;
+        next if @vars && !grep( matchvar($key, $_), @vars );
+        if ($usageOnly) {
+            if (
+                ($package ne 'dumpvar' or $key ne 'stab')
+                    and
+                (ref(\$val) eq 'GLOB')
+            ) {
+                globUsage(\$val, $key)
+            }
+        }
+        else {
+            dumpglob(0,$key, $val, 0, $m);
+        }
     }
     if ($usageOnly) {
-      print "String space: $TotalStrings bytes in $Strings strings.\n";
-      $CompleteTotal += $TotalStrings;
-      print "Grand total = $CompleteTotal bytes (1 level deep) + overhead.\n";
+        print "String space: $TotalStrings bytes in $Strings strings.\n";
+        $CompleteTotal += $TotalStrings;
+        print "Grand total = $CompleteTotal bytes (1 level deep) + overhead.\n";
     }
 }
 
diff --git a/lib/perl5db.t b/lib/perl5db.t
index ab35f993e0dc..f91b1d1e4b30 100644
--- a/lib/perl5db.t
+++ b/lib/perl5db.t
@@ -3662,6 +3662,46 @@ EOS
     $wrapper->contents_like(qr/print "2\\n"/, "break immediately after defining problem");
 }
 
+{
+    # gh #23663 (variant 1)
+    my $wrapper = DebugWrap->new(
+        {
+            cmds =>
+            [
+                'b 4',
+                'X',
+                'c',
+                'q',
+            ],
+            prog => \1,
+        }
+    );
+
+    $wrapper->contents_unlike(
+        qr/Use of each\(\) on hash after insertion without resetting hash iterator results in undefined behavior/,
+        q/gh-23663: 'X' command does not warn about undefined behavior/,
+       );
+
+    # gh #23663 (variant 2)
+    $wrapper = DebugWrap->new(
+        {
+            cmds =>
+            [
+                'b 4',
+                'V main',
+                'c',
+                'q',
+            ],
+            prog => \1,
+        }
+    );
+
+    $wrapper->contents_unlike(
+        qr/Use of each\(\) on hash after insertion without resetting hash iterator results in undefined behavior/,
+        q/gh-23663: 'V main' command does not warn about undefined behavior/,
+       );
+}
+
 done_testing();
 
 END {