diff --git a/micrograd/nn.py b/micrograd/nn.py
index 30d5d777..d612cd51 100644
--- a/micrograd/nn.py
+++ b/micrograd/nn.py
@@ -16,8 +16,10 @@ def __init__(self, nin, nonlin=True):
         self.w = [Value(random.uniform(-1,1)) for _ in range(nin)]
         self.b = Value(0)
         self.nonlin = nonlin
+        self.nin = nin
 
     def __call__(self, x):
+        assert len(x) == self.nin, "Shape mismatch between input and given nin value"
         act = sum((wi*xi for wi,xi in zip(self.w, x)), self.b)
         return act.relu() if self.nonlin else act