Index: src/whereexpr.c
==================================================================
--- src/whereexpr.c
+++ src/whereexpr.c
@@ -218,15 +218,24 @@
     assert( !ExprHasProperty(pRight, EP_IntValue) );
      z = (u8*)pRight->u.zToken;
   }
   if( z ){
 
-    /* Count the number of prefix characters prior to the first wildcard */
+    /* Count the number of prefix characters prior to the first wildcard.
+    ** If the underlying database has a UTF16LE encoding, then only consider
+    ** ASCII characters.  Note that the encoding of z[] is UTF8 - we are
+    ** dealing with only UTF8 here in this code, but the database engine
+    ** itself might be processing content using a different encoding. */
     cnt = 0;
     while( (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2] ){
       cnt++;
-      if( c==wc[3] && z[cnt]!=0 ) cnt++;
+      if( c==wc[3] && z[cnt]!=0 ){
+        cnt++;
+      }else if( c>=0x80 && ENC(db)==SQLITE_UTF16LE ){
+         cnt--;
+         break;
+      }
     }
 
     /* The optimization is possible only if (1) the pattern does not begin
     ** with a wildcard and if (2) the non-wildcard prefix does not end with
     ** an (illegal 0xff) character, or (3) the pattern does not consist of
@@ -237,11 +246,11 @@
     ** removed.  */
     if( (cnt>1 || (cnt>0 && z[0]!=wc[3])) && 255!=(u8)z[cnt-1] ){
       Expr *pPrefix;
 
       /* A "complete" match if the pattern ends with "*" or "%" */
-      *pisComplete = c==wc[0] && z[cnt+1]==0;
+      *pisComplete = c==wc[0] && z[cnt+1]==0 && ENC(db)!=SQLITE_UTF16LE;
 
       /* Get the pattern prefix.  Remove all escapes from the prefix. */
       pPrefix = sqlite3Expr(db, TK_STRING, (char*)z);
       if( pPrefix ){
         int iFrom, iTo;