diff --git a/plugins/spellchecker/src/com/intellij/spellchecker/compress/CompressedDictionary.java b/plugins/spellchecker/src/com/intellij/spellchecker/compress/CompressedDictionary.java
index 4b3be754dae1..14127d894d1e 100644
--- a/plugins/spellchecker/src/com/intellij/spellchecker/compress/CompressedDictionary.java
+++ b/plugins/spellchecker/src/com/intellij/spellchecker/compress/CompressedDictionary.java
@@ -121,6 +121,7 @@ public final class CompressedDictionary implements Dictionary {
     }
     try {
       UnitBitSet bs = encoder.encode(word, false);
+      if (bs == null) return false;
       byte[] compressed = UnitBitSet.getBytes(bs);
       int index = -1;
       for (int i = 0; i < lengths.length; i++) {
@@ -179,6 +180,7 @@ public final class CompressedDictionary implements Dictionary {
         String transformed = transform.transform(s);
         if (transformed != null) {
           UnitBitSet bs = encoder.encode(transformed, true);
+          if (bs == null) return;
           byte[] compressed = UnitBitSet.getBytes(bs);
           dictionary.addToDictionary(compressed);
         }
diff --git a/plugins/spellchecker/src/com/intellij/spellchecker/compress/Encoder.java b/plugins/spellchecker/src/com/intellij/spellchecker/compress/Encoder.java
index 543f3fcc07d9..e9ade3511131 100644
--- a/plugins/spellchecker/src/com/intellij/spellchecker/compress/Encoder.java
+++ b/plugins/spellchecker/src/com/intellij/spellchecker/compress/Encoder.java
@@ -1,6 +1,7 @@
 package com.intellij.spellchecker.compress;
 
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.text.MessageFormat;
 
@@ -21,8 +22,9 @@ public final class Encoder {
     return alphabet;
   }
 
+  @Nullable
   public UnitBitSet encode(@NotNull CharSequence letters, boolean force) throws EncodingException {
-    assert UnitBitSet.MAX_CHARS_IN_WORD >= letters.length() : "Word is too long ";
+    if (UnitBitSet.MAX_CHARS_IN_WORD >= letters.length()) return null;
     UnitBitSet bs = new UnitBitSet();
     for (int i = 0; i < letters.length() - 1 + 1; i++) {
       char letter = letters.charAt(i);