diff --git a/corpus/plpgsql/block.txt b/corpus/plpgsql/block.txt
index 86c3f38..dc176bf 100644
--- a/corpus/plpgsql/block.txt
+++ b/corpus/plpgsql/block.txt
@@ -147,6 +147,7 @@ DO $$
 BEGIN
     SELECT 1;
     foo.bar = lower(foo.baz);
+    foo.bar := lower(foo.baz);
     RETURN 2;
 END
 $$;
@@ -165,6 +166,11 @@ $$;
           (function_call
             (identifier)
             (identifier)))
+        (assign_statement
+          (identifier)
+          (function_call
+            (identifier)
+            (identifier)))
         (return_statement
           (number)))
       (dollar_quote))))
diff --git a/grammar.js b/grammar.js
index 24878df..cf0c447 100644
--- a/grammar.js
+++ b/grammar.js
@@ -459,7 +459,7 @@ module.exports = grammar({
       optional($.execute_using),
     ),
     execute_using: $ => seq(kw("using"), commaSep1($._value_expression)),
-    assign_statement: $ => seq($.identifier, "=", $._value_expression),
+    assign_statement: $ => seq($.identifier, choice("=", ":="), $._value_expression),
     return_statement: $ => seq(kw("return"), choice(
       seq(kw("query"), $.select_statement),
       seq(kw("query"), $.execute_statement),