diff --git a/src/search/PhutilSearchStemmer.php b/src/search/PhutilSearchStemmer.php
--- a/src/search/PhutilSearchStemmer.php
+++ b/src/search/PhutilSearchStemmer.php
@@ -45,7 +45,16 @@
       $loaded = true;
     }
 
-    return Porter::stem($normalized_token);
+    $stem = Porter::stem($normalized_token);
+
+    // If the stem is too short, it won't be a candidate for indexing. These
+    // tokens are also likely to be acronyms (like "DNS") rather than real
+    // English words.
+    if (strlen($stem) < 3) {
+      return $normalized_token;
+    }
+
+    return $stem;
   }
 
 }
diff --git a/src/search/__tests__/PhutilSearchStemmerTestCase.php b/src/search/__tests__/PhutilSearchStemmerTestCase.php
--- a/src/search/__tests__/PhutilSearchStemmerTestCase.php
+++ b/src/search/__tests__/PhutilSearchStemmerTestCase.php
@@ -30,6 +30,11 @@
 
       // Stems should be normalized.
       'DOG' => 'dog',
+
+      // If stemming would bring a token under 3 characters, it should not
+      // be stemmed.
+      'dns' => 'dns',
+      'nis' => 'nis',
     );
 
     $stemmer = new PhutilSearchStemmer();