diff --git a/parse.y b/parse.y
index e6fee29595e26e..38f7690ccc01d7 100644
--- a/parse.y
+++ b/parse.y
@@ -1774,14 +1774,18 @@ expr		: command_call
 			p->ctxt.in_kwarg = 1;
 			$<tbl>$ = push_pvtbl(p);
 		    }
+		    {
+			$<tbl>$ = push_pktbl(p);
+		    }
 		  p_top_expr_body
 		    {
+			pop_pktbl(p, $<tbl>4);
 			pop_pvtbl(p, $<tbl>3);
 			p->ctxt.in_kwarg = $<ctxt>2.in_kwarg;
 		    /*%%%*/
-			$$ = NEW_CASE3($1, NEW_IN($4, 0, 0, &@4), &@$);
+			$$ = NEW_CASE3($1, NEW_IN($5, 0, 0, &@5), &@$);
 		    /*% %*/
-		    /*% ripper: case!($1, in!($4, Qnil, Qnil)) %*/
+		    /*% ripper: case!($1, in!($5, Qnil, Qnil)) %*/
 		    }
 		| arg keyword_in
 		    {
@@ -1792,14 +1796,18 @@ expr		: command_call
 			p->ctxt.in_kwarg = 1;
 			$<tbl>$ = push_pvtbl(p);
 		    }
+		    {
+			$<tbl>$ = push_pktbl(p);
+		    }
 		  p_top_expr_body
 		    {
+			pop_pktbl(p, $<tbl>4);
 			pop_pvtbl(p, $<tbl>3);
 			p->ctxt.in_kwarg = $<ctxt>2.in_kwarg;
 		    /*%%%*/
-			$$ = NEW_CASE3($1, NEW_IN($4, NEW_TRUE(&@4), NEW_FALSE(&@4), &@4), &@$);
+			$$ = NEW_CASE3($1, NEW_IN($5, NEW_TRUE(&@5), NEW_FALSE(&@5), &@5), &@$);
 		    /*% %*/
-		    /*% ripper: case!($1, in!($4, Qnil, Qnil)) %*/
+		    /*% ripper: case!($1, in!($5, Qnil, Qnil)) %*/
 		    }
 		| arg %prec tLBRACE_ARG
 		;
diff --git a/test/ruby/test_pattern_matching.rb b/test/ruby/test_pattern_matching.rb
index 36731e14f9609d..fbb934dc84a290 100644
--- a/test/ruby/test_pattern_matching.rb
+++ b/test/ruby/test_pattern_matching.rb
@@ -1570,6 +1570,18 @@ def test_one_line
     assert_equal false, (1 in 2)
   end
 
+  def test_bug18990
+    {a: 0} => a:
+    assert_equal 0, a
+    {a: 0} => a:
+    assert_equal 0, a
+
+    {a: 0} in a:
+    assert_equal 0, a
+    {a: 0} in a:
+    assert_equal 0, a
+  end
+
   ################################################################
 
   def test_single_pattern_error_value_pattern