diff --git a/src/Raku/ast/code.rakumod b/src/Raku/ast/code.rakumod
index d1fd1cb38d4..d2bd18a052e 100644
--- a/src/Raku/ast/code.rakumod
+++ b/src/Raku/ast/code.rakumod
@@ -909,6 +909,7 @@ class RakuAST::Block
 
     method clear-attachments() {
         self.clear-handler-attachments();
+        self.clear-used-dynamic-variables();
         self.clear-placeholder-attachments();
         self.clear-phaser-attachments();
         Nil
@@ -1350,6 +1351,7 @@ class RakuAST::Routine
 
     method clear-attachments() {
         self.clear-handler-attachments();
+        self.clear-used-dynamic-variables();
         self.clear-placeholder-attachments();
         self.clear-phaser-attachments();
         Nil
diff --git a/src/Raku/ast/compunit.rakumod b/src/Raku/ast/compunit.rakumod
index dea5f6b0d08..39d16ec7b4c 100644
--- a/src/Raku/ast/compunit.rakumod
+++ b/src/Raku/ast/compunit.rakumod
@@ -158,6 +158,7 @@ class RakuAST::CompUnit
         nqp::setelems($!init-phasers, 0);
         nqp::setelems($!end-phasers, 0);
         self.clear-handler-attachments();
+        self.clear-used-dynamic-variables();
         Nil
     }
 
diff --git a/src/Raku/ast/scoping.rakumod b/src/Raku/ast/scoping.rakumod
index 6ae05970d71..5ae60764c0f 100644
--- a/src/Raku/ast/scoping.rakumod
+++ b/src/Raku/ast/scoping.rakumod
@@ -17,6 +17,8 @@ class RakuAST::LexicalScope
     has Mu $!catch-handlers;
     has Mu $!control-handlers;
 
+    has Hash $!used-dynamic-variables;
+
     method IMPL-QAST-DECLS(RakuAST::IMPL::QASTContext $context) {
         my $stmts := QAST::Stmts.new();
 
@@ -237,6 +239,22 @@ class RakuAST::LexicalScope
         Nil
     }
 
+    method add-used-dynamic-variable(RakuAST::Var::Dynamic $var) {
+        unless nqp::isconcrete($!used-dynamic-variables) {
+            nqp::bindattr(self, RakuAST::LexicalScope, '$!used-dynamic-variables', {});
+        }
+        $!used-dynamic-variables{$var.name} := $var;
+    }
+
+    method clear-used-dynamic-variables() {
+        nqp::bindattr(self, RakuAST::LexicalScope, '$!used-dynamic-variables', {});
+    }
+
+    method uses-dynamic-variable(str $name) {
+        nqp::isconcrete($!used-dynamic-variables)
+            && nqp::existskey($!used-dynamic-variables, $name)
+    }
+
     method IMPL-WRAP-SCOPE-HANDLER-QAST(RakuAST::IMPL::QASTContext $context, Mu $statements,
                                         Bool :$is-handler) {
         # If it's an exception handler, add rethrow logic.
diff --git a/src/Raku/ast/variable-access.rakumod b/src/Raku/ast/variable-access.rakumod
index 2b85e6908f5..a042e423d52 100644
--- a/src/Raku/ast/variable-access.rakumod
+++ b/src/Raku/ast/variable-access.rakumod
@@ -88,6 +88,7 @@ class RakuAST::Var::Lexical::Setting
 class RakuAST::Var::Dynamic
   is RakuAST::Var
   is RakuAST::Lookup
+  is RakuAST::Attaching
 {
     has str $.name;
 
@@ -111,6 +112,10 @@ class RakuAST::Var::Dynamic
         Nil
     }
 
+    method attach(RakuAST::Resolver $resolver) {
+        $resolver.current-scope.add-used-dynamic-variable(self);
+    }
+
     method IMPL-EXPR-QAST(RakuAST::IMPL::QASTContext $context) {
         # If it's resolved in the current scope, just a lexical access.
         if self.is-resolved {
diff --git a/src/Raku/ast/variable-declaration.rakumod b/src/Raku/ast/variable-declaration.rakumod
index 89e501cf6c1..bc21c0dc197 100644
--- a/src/Raku/ast/variable-declaration.rakumod
+++ b/src/Raku/ast/variable-declaration.rakumod
@@ -405,6 +405,7 @@ class RakuAST::VarDeclaration::Simple
   is RakuAST::Meta
   is RakuAST::Attaching
   is RakuAST::BeginTime
+  is RakuAST::CheckTime
   is RakuAST::Term
   is RakuAST::Doc::DeclaratorTarget
 {
@@ -417,6 +418,7 @@ class RakuAST::VarDeclaration::Simple
     has RakuAST::SemiList    $.shape;
     has RakuAST::Package     $!attribute-package;
     has RakuAST::Method      $!accessor;
+    has Bool                 $!is-illegal-postdeclaration;
 
     has Mu $!container-initializer;
     has Mu $!package;
@@ -532,6 +534,11 @@ class RakuAST::VarDeclaration::Simple
             nqp::bindattr(self, RakuAST::VarDeclaration::Simple, '$!package',
                 $package);
         }
+
+        nqp::bindattr(self, RakuAST::VarDeclaration::Simple, '$!is-illegal-postdeclaration', False);
+        if self.twigil eq '*' && $resolver.current-scope.uses-dynamic-variable(self.name) {
+            nqp::bindattr(self, RakuAST::VarDeclaration::Simple, '$!is-illegal-postdeclaration', True);
+        }
     }
 
     method PERFORM-BEGIN(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
@@ -660,6 +667,12 @@ class RakuAST::VarDeclaration::Simple
         }
     }
 
+    method PERFORM-CHECK(RakuAST::Resolver $resolver, RakuAST::IMPL::QASTContext $context) {
+        self.add-sorry: $resolver.build-exception:
+            'X::Dynamic::Postdeclaration', :symbol(self.name)
+            if $!is-illegal-postdeclaration;
+    }
+
     method PRODUCE-IMPLICIT-LOOKUPS() {
         my @lookups;
         my str $scope := self.scope;