diff --git a/textplot/text.py b/textplot/text.py
index <HASH>..<HASH> 100644
--- a/textplot/text.py
+++ b/textplot/text.py
@@ -162,7 +162,8 @@ class Text(object):
         signals = []
 
         for term in query_text.terms:
-            signals.append(self.kde(term, **kwargs))
+            if term in self.terms:
+                signals.append(self.kde(term, **kwargs))
 
         result = np.zeros(signals[0].size)
         for signal in signals: result += signal
When running a KDE query, check that a term is present in the base text before trying to generate the estimate.