Index: ext/session/sqlite3session.c
==================================================================
--- ext/session/sqlite3session.c
+++ ext/session/sqlite3session.c
@@ -1792,16 +1792,16 @@
 ** set *pRc to SQLITE_NOMEM and return non-zero.
 */
 static int sessionBufferGrow(SessionBuffer *p, int nByte, int *pRc){
   if( *pRc==SQLITE_OK && p->nAlloc-p->nBuf<nByte ){
     u8 *aNew;
-    int nNew = p->nAlloc ? p->nAlloc : 128;
+    i64 nNew = p->nAlloc ? p->nAlloc : 128;
     do {
       nNew = nNew*2;
-    }while( nNew<(p->nBuf+nByte) );
+    }while( (nNew-p->nBuf)<nByte );
 
-    aNew = (u8 *)sqlite3_realloc(p->aBuf, nNew);
+    aNew = (u8 *)sqlite3_realloc64(p->aBuf, nNew);
     if( 0==aNew ){
       *pRc = SQLITE_NOMEM;
     }else{
       p->aBuf = aNew;
       p->nAlloc = nNew;