diff --git a/tree-sitter-p4/grammar.js b/tree-sitter-p4/grammar.js
index b656965..8192a1f 100644
--- a/tree-sitter-p4/grammar.js
+++ b/tree-sitter-p4/grammar.js
@@ -64,12 +64,14 @@ export default grammar({
         instantiation: $ => seq($.typeRef, '(', optional($.parameter_list), ')', $.identifier),
 
         // Declarations
-        declaration: $ => seq(choice($.parserDeclaration, $.parserTypeDeclaration, $.type_declaration)),
+        declaration: $ => seq(choice($.parserDeclaration, $.parserTypeDeclaration, $.type_declaration, $.function_declaration)),
 
         type_declaration: $=> choice($.struct_declaration),
         struct_declaration: $ => seq($.struct, $.identifier, '{', optional($.struct_declaration_fields), '}'),
         struct_declaration_fields: $=> repeat1(seq($.variableDeclaration)),
 
+        function_declaration: $=> seq($.typeRef, $.identifier, $.parameters, $.statement),
+
         // Make separate productions for the parser type and the parser type declaration because the latter can have type parameters.
         parserTypeDeclaration: $ => seq(optional($.annotations), $.parser, field('parser_name', $.identifier), optional($.typeParameters), $.parameters),
         parserDeclaration: $ => seq($.parserType, '{', optional($.parserLocalElements), $.parserStates, '}'),
diff --git a/tree-sitter-p4/test/corpus/declarations.txt b/tree-sitter-p4/test/corpus/declarations.txt
index 0a7983c..7d57b4d 100644
--- a/tree-sitter-p4/test/corpus/declarations.txt
+++ b/tree-sitter-p4/test/corpus/declarations.txt
@@ -265,3 +265,40 @@ struct Testing {
  )
 )
 
+=========================
+Simple Function Declaration
+=========================
+bool functionb() {
+  string fieldA;
+};
+---
+(p4program
+ (declaration
+  (function_declaration
+   (typeRef
+    (baseType
+     (bool)
+    )
+   )
+   (identifier)
+   (parameters
+   )
+   (statement
+    (blockStatement
+     (statements
+      (statement
+       (variableDeclaration
+        (typeRef
+         (baseType
+          (string)
+         )
+        )
+       (identifier)
+       )
+      )
+     )
+    )
+   )
+  )
+ )
+)