diff --git a/pymc3/distributions/mixture.py b/pymc3/distributions/mixture.py
index 215667ec1b..b0640542d6 100644
--- a/pymc3/distributions/mixture.py
+++ b/pymc3/distributions/mixture.py
@@ -138,7 +138,10 @@ def random_choice(*args, **kwargs):
         comp_samples = self._comp_samples(point=point, size=size, repeat=repeat)
 
         if comp_samples.ndim > 1:
-            return np.squeeze(comp_samples[np.arange(w_samples.size), w_samples])
+            row_ix = (np.arange(w_samples.shape[0])
+                        .reshape([w_samples.shape[0]] + [1 for _ in w_samples.shape[1:]]))
+
+            return np.squeeze(comp_samples[row_ix, w_samples])
         else:
             return np.squeeze(comp_samples[w_samples])