diff --git a/lib/prism/node_ext.rb b/lib/prism/node_ext.rb
index 1bb3ebcf5f921b..a05123d1bb3aa5 100644
--- a/lib/prism/node_ext.rb
+++ b/lib/prism/node_ext.rb
@@ -286,7 +286,9 @@ def signature
         case param
         when MultiTargetNode
           names << [:req]
-        when NoKeywordsParameterNode, KeywordRestParameterNode, ForwardingParameterNode
+        when NoKeywordsParameterNode, KeywordRestParameterNode,
+            NoBlockParameterNode, BlockParameterNode,
+            ForwardingParameterNode
           # Invalid syntax, e.g. "def f(**nil, ...)" moves the NoKeywordsParameterNode to posts
           raise "Invalid syntax"
         else
diff --git a/lib/prism/translation/parser/builder.rb b/lib/prism/translation/parser/builder.rb
index 6b620c25bc9658..7fc3bba6b74718 100644
--- a/lib/prism/translation/parser/builder.rb
+++ b/lib/prism/translation/parser/builder.rb
@@ -7,12 +7,14 @@ class Parser
       # A builder that knows how to convert more modern Ruby syntax
       # into whitequark/parser gem's syntax tree.
       class Builder < ::Parser::Builders::Default
-        # It represents the `it` block argument, which is not yet implemented in the Parser gem.
+        # It represents the `it` block argument, which is not yet implemented in
+        # the Parser gem.
         def itarg
           n(:itarg, [:it], nil)
         end
 
-        # The following three lines have been added to support the `it` block parameter syntax in the source code below.
+        # The following three lines have been added to support the `it` block
+        # parameter syntax in the source code below.
         #
         #   if args.type == :itarg
         #     block_type = :itblock
@@ -56,6 +58,12 @@ def block(method_call, begin_t, args, body, end_t)
               method_call.loc.with_expression(join_exprs(method_call, block)))
           end
         end
+
+        # def foo(&nil); end
+        #         ^^^^
+        def blocknilarg(amper_t, nil_t)
+          n0(:blocknilarg, arg_prefix_map(amper_t, nil_t))
+        end
       end
     end
   end
diff --git a/lib/prism/translation/parser/compiler.rb b/lib/prism/translation/parser/compiler.rb
index 37951a1d400159..21aa7796c3c9d4 100644
--- a/lib/prism/translation/parser/compiler.rb
+++ b/lib/prism/translation/parser/compiler.rb
@@ -1390,6 +1390,12 @@ def visit_nil_node(node)
           builder.nil(token(node.location))
         end
 
+        # def foo(&nil); end
+        #         ^^^^
+        def visit_no_block_parameter_node(node)
+          builder.blocknilarg(token(node.operator_loc), token(node.keyword_loc))
+        end
+
         # def foo(**nil); end
         #         ^^^^^
         def visit_no_keywords_parameter_node(node)
diff --git a/prism/config.yml b/prism/config.yml
index 0736f5a0bf2dfb..7527e01070b2a5 100644
--- a/prism/config.yml
+++ b/prism/config.yml
@@ -4065,6 +4065,9 @@ nodes:
           - on error: NoKeywordsParameterNode
           # On parsing error of `f(..., ...)`, the first forwarding parameter is moved here:
           - on error: ForwardingParameterNode
+          # On parsing error of `f(&nil, &foo)`/`f(&foo, &nil)`, the first forwarding parameter is moved here:
+          - on error: BlockParameterNode
+          - on error: NoBlockParameterNode
       - name: keywords
         type: node[]
         kind:
diff --git a/prism/prism.c b/prism/prism.c
index 81768024f2abf6..56cb9e3fb3f771 100644
--- a/prism/prism.c
+++ b/prism/prism.c
@@ -13949,7 +13949,7 @@ parse_parameters(
                 pm_token_t operator = parser->previous;
                 pm_node_t *param;
 
-                if (accept1(parser, PM_TOKEN_KEYWORD_NIL)) {
+                if (parser->version >= PM_OPTIONS_VERSION_CRUBY_4_1 && accept1(parser, PM_TOKEN_KEYWORD_NIL)) {
                     param = (pm_node_t *) pm_no_block_parameter_node_create(parser, &operator, &parser->previous);
                 } else {
                     pm_token_t name = {0};
diff --git a/test/prism/errors/3.3-4.0/noblock.txt b/test/prism/errors/3.3-4.0/noblock.txt
new file mode 100644
index 00000000000000..07939041bb0d7a
--- /dev/null
+++ b/test/prism/errors/3.3-4.0/noblock.txt
@@ -0,0 +1,6 @@
+def foo(&nil)
+         ^~~ unexpected 'nil'; expected a `)` to close the parameters
+            ^ unexpected ')', expecting end-of-input
+            ^ unexpected ')', ignoring it
+end
+
diff --git a/test/prism/errors/4.1/multiple_blocks.txt b/test/prism/errors/4.1/multiple_blocks.txt
new file mode 100644
index 00000000000000..7e8433cf82abd2
--- /dev/null
+++ b/test/prism/errors/4.1/multiple_blocks.txt
@@ -0,0 +1,12 @@
+def foo(&nil, &nil); end
+              ^ unexpected parameter order
+              ^~~~ multiple block parameters; only one block is allowed
+
+def foo(&foo, &nil); end
+              ^ unexpected parameter order
+              ^~~~ multiple block parameters; only one block is allowed
+
+def foo(&nil, &foo); end
+              ^ unexpected parameter order
+              ^~~~ multiple block parameters; only one block is allowed
+
diff --git a/test/prism/fixtures/4.1/noblock.txt b/test/prism/fixtures/4.1/noblock.txt
new file mode 100644
index 00000000000000..2395393e228f10
--- /dev/null
+++ b/test/prism/fixtures/4.1/noblock.txt
@@ -0,0 +1,4 @@
+def foo(&nil)
+end
+
+-> (&nil) {}
diff --git a/test/prism/locals_test.rb b/test/prism/locals_test.rb
index 48449018041dcf..bcb964aff67568 100644
--- a/test/prism/locals_test.rb
+++ b/test/prism/locals_test.rb
@@ -30,7 +30,7 @@ class LocalsTest < TestCase
       "command_method_call_2.txt",
 
       # https://bugs.ruby-lang.org/issues/21669
-      "4.1/void_value.txt"
+      "4.1/void_value.txt",
     ]
 
     Fixture.each_for_current_ruby(except: except) do |fixture|
@@ -207,7 +207,7 @@ def prism_locals(source)
               end
             end
 
-            if params.block
+            if params.block.is_a?(BlockParameterNode)
               sorted << (params.block.name || :&)
             end
 
diff --git a/test/prism/ruby/ripper_test.rb b/test/prism/ruby/ripper_test.rb
index 39cb9395ab680e..00cf470e0ec6e5 100644
--- a/test/prism/ruby/ripper_test.rb
+++ b/test/prism/ruby/ripper_test.rb
@@ -40,6 +40,9 @@ class RipperTest < TestCase
     # https://bugs.ruby-lang.org/issues/21669
     incorrect << "4.1/void_value.txt"
 
+    # https://bugs.ruby-lang.org/issues/19979
+    incorrect << "4.1/noblock.txt"
+
     # Skip these tests that we haven't implemented yet.
     omitted_sexp_raw = [
       "bom_leading_space.txt",