Index: tool/index_usage.c
==================================================================
--- tool/index_usage.c
+++ tool/index_usage.c
@@ -184,11 +184,11 @@
         int n;
         /* printf("EXPLAIN: %s\n", zExplain); */
         z1 = strstr(zExplain, " USING INDEX ");
         if( z1==0 ) continue;
         z1 += 13;
-        for(z2=z1+1; z2[1] && z2[1]!='('; z2++){}
+        for(z2=z1+1; z2[0] && z2[1]!='('; z2++){}
         n = z2 - z1;
         if( zUsing && sqlite3_strnicmp(zUsing, z1, n)==0 ){
           printf("Using %s:\n%s\n", zUsing, zLog);
           fflush(stdout);
         }