diff --git a/demo/src/app/views/root.zig b/demo/src/app/views/root.zig
index e0ade83..1353b9e 100644
--- a/demo/src/app/views/root.zig
+++ b/demo/src/app/views/root.zig
@@ -3,8 +3,13 @@ const jetzig = @import("jetzig");
 pub fn index(request: *jetzig.Request, data: *jetzig.Data) !jetzig.View {
     var root = try data.object();
     try root.put("message", data.string("Welcome to Jetzig!"));
+    try root.put("number", data.integer(customFunction(100, 200, 300)));
 
     try request.response.headers.append("x-example-header", "example header value");
 
     return request.render(.ok);
 }
+
+fn customFunction(a: i32, b: i32, c: i32) i32 {
+    return a + b + c;
+}
diff --git a/src/GenerateRoutes.zig b/src/GenerateRoutes.zig
index 3ebbf6e..119f116 100644
--- a/src/GenerateRoutes.zig
+++ b/src/GenerateRoutes.zig
@@ -430,6 +430,11 @@ fn parseFunction(
         var args = std.ArrayList(Arg).init(self.allocator);
         defer args.deinit();
 
+        if (!isActionFunctionName(function_name)) {
+            self.allocator.free(function_name);
+            return null;
+        }
+
         while (it.next()) |arg| {
             if (arg.name_token) |arg_token| {
                 const arg_name = self.ast.tokenSlice(arg_token);
@@ -478,3 +483,11 @@ fn parseTypeExpr(self: *Self, node: std.zig.Ast.Node) ![]const u8 {
 fn asNodeIndex(index: usize) std.zig.Ast.Node.Index {
     return @as(std.zig.Ast.Node.Index, @intCast(index));
 }
+
+fn isActionFunctionName(name: []const u8) bool {
+    inline for (@typeInfo(jetzig.views.Route.Action).Enum.fields) |field| {
+        if (std.mem.eql(u8, field.name, name)) return true;
+    }
+
+    return false;
+}