diff --git a/facil.io/lib/facil/http/websockets.c b/facil.io/lib/facil/http/websockets.c
index 87353ef..1e882da 100644
--- a/facil.io/lib/facil/http/websockets.c
+++ b/facil.io/lib/facil/http/websockets.c
@@ -96,7 +96,7 @@ void free_ws_buffer(ws_s *owner, struct buffer_s buff) {
 Create/Destroy the websocket object (prototypes)
 */
 
-static ws_s *new_websocket();
+static ws_s *new_websocket(intptr_t uuid);
 static void destroy_ws(ws_s *ws);
 
 /*******************************************************************************
diff --git a/src/router.zig b/src/router.zig
index 9b99453..e6bfe23 100644
--- a/src/router.zig
+++ b/src/router.zig
@@ -75,6 +75,41 @@ pub fn handle_func_unbound(self: *Router, path: []const u8, h: zap.HttpRequestFn
 pub fn handle_func(self: *Router, path: []const u8, instance: *anyopaque, handler: anytype) !void {
     // TODO: assert type of instance has handler
 
+    // Introspection checks on handler type
+    comptime {
+        const hand_info = @typeInfo(@TypeOf(handler));
+
+        // Need to check:
+        // 1) handler is function pointer
+        const f = blk: {
+            if (hand_info == .Pointer) {
+                const inner = @typeInfo(hand_info.Pointer.child);
+                if (inner == .Fn) {
+                    break :blk inner.Fn;
+                }
+            }
+            @compileError("Expected handler to be a function pointer. Found " ++
+                @typeName(@TypeOf(handler)));
+        };
+
+        // 2) snd arg is zap.Request
+        if (f.params.len != 2) {
+            @compileError("Expected handler to have two paramters");
+        }
+        const arg_type = f.params[1].type.?;
+        if (arg_type != zap.Request) {
+            @compileError("Expected handler's second argument to be of type zap.Request. Found " ++
+                @typeName(arg_type));
+        }
+
+        // 3) handler returns void
+        const ret_info = @typeInfo(f.return_type.?);
+        if (ret_info != .Void) {
+            @compileError("Expected handler's return type to be void. Found " ++
+                @typeName(f.return_type.?));
+        }
+    }
+
     if (path.len == 0) {
         return RouterError.EmptyPath;
     }