Index: src/build.c
==================================================================
--- src/build.c
+++ src/build.c
@@ -4183,11 +4183,13 @@
     for(j=0; j<pIdx->nKeyCol; j++){
       char *zCol;
       assert( pIdx->aiColumn[j]>=0 );
       zCol = pTab->aCol[pIdx->aiColumn[j]].zName;
       if( j ) sqlite3StrAccumAppend(&errMsg, ", ", 2);
-      sqlite3XPrintf(&errMsg, "%s.%s", pTab->zName, zCol);
+      sqlite3StrAccumAppendAll(&errMsg, pTab->zName);
+      sqlite3StrAccumAppend(&errMsg, ".", 1);
+      sqlite3StrAccumAppendAll(&errMsg, zCol);
     }
   }
   zErr = sqlite3StrAccumFinish(&errMsg);
   sqlite3HaltConstraint(pParse, 
     IsPrimaryKeyIndex(pIdx) ? SQLITE_CONSTRAINT_PRIMARYKEY