Index: ext/rbu/sqlite3rbu.c
==================================================================
--- ext/rbu/sqlite3rbu.c
+++ ext/rbu/sqlite3rbu.c
@@ -94,10 +94,17 @@
 #endif
 
 /* Maximum number of prepared UPDATE statements held by this module */
 #define SQLITE_RBU_UPDATE_CACHESIZE 16
 
+/* Delta checksums disabled by default.  Compile with -DRBU_ENABLE_DELTA_CKSUM
+** to enable checksum verification.
+*/
+#ifndef RBU_ENABLE_DELTA_CKSUM
+# define RBU_ENABLE_DELTA_CKSUM 0
+#endif
+
 /*
 ** Swap two objects of type TYPE.
 */
 #if !defined(SQLITE_AMALGAMATION)
 # define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}
@@ -468,10 +475,11 @@
   *pLen -= z - zStart;
   *pz = (char*)z;
   return v;
 }
 
+#if RBU_ENABLE_DELTA_CKSUM
 /*
 ** Compute a 32-bit checksum on the N-byte buffer.  Return the result.
 */
 static unsigned int rbuDeltaChecksum(const char *zIn, size_t N){
   const unsigned char *z = (const unsigned char *)zIn;
@@ -502,10 +510,11 @@
     case 1:   sum3 += (z[0] << 24);
     default:  ;
   }
   return sum3;
 }
+#endif
 
 /*
 ** Apply a delta.
 **
 ** The output buffer should be big enough to hold the whole output
@@ -532,11 +541,11 @@
   int lenDelta,          /* Length of the delta */
   char *zOut             /* Write the output into this preallocated buffer */
 ){
   unsigned int limit;
   unsigned int total = 0;
-#ifndef FOSSIL_OMIT_DELTA_CKSUM_TEST
+#if RBU_ENABLE_DELTA_CKSUM
   char *zOrigOut = zOut;
 #endif
 
   limit = rbuDeltaGetInt(&zDelta, &lenDelta);
   if( *zDelta!='\n' ){
@@ -587,11 +596,11 @@
         break;
       }
       case ';': {
         zDelta++; lenDelta--;
         zOut[0] = 0;
-#ifndef FOSSIL_OMIT_DELTA_CKSUM_TEST
+#if RBU_ENABLE_DELTA_CKSUM
         if( cnt!=rbuDeltaChecksum(zOrigOut, total) ){
           /* ERROR:  bad checksum */
           return -1;
         }
 #endif