Index: src/vdbemem.c
==================================================================
--- src/vdbemem.c
+++ src/vdbemem.c
@@ -1040,13 +1040,13 @@
     if( SQLITE_OK==sqlite3ValueFromExpr(db,pExpr->pLeft,enc,affinity,&pVal) 
      && pVal!=0
     ){
       sqlite3VdbeMemNumerify(pVal);
       if( pVal->u.i==SMALLEST_INT64 ){
-        pVal->flags &= MEM_Int;
+        pVal->flags &= ~MEM_Int;
         pVal->flags |= MEM_Real;
-        pVal->r = (double)LARGEST_INT64;
+        pVal->r = (double)SMALLEST_INT64;
       }else{
         pVal->u.i = -pVal->u.i;
       }
       pVal->r = -pVal->r;
       sqlite3ValueApplyAffinity(pVal, affinity, enc);

Index: test/alter4.test
==================================================================
--- test/alter4.test
+++ test/alter4.test
@@ -332,6 +332,27 @@
   execsql {
     SELECT sql FROM sqlite_temp_master WHERE name = 't4';
   }
 } [list $::sql]
 
+
+# Test that a default value equal to -1 multipied by the smallest possible
+# 64-bit integer is correctly converted to a real.
+do_execsql_test alter4-9.1 {
+  CREATE TABLE t5(
+    a INTEGER DEFAULT -9223372036854775808,
+    b INTEGER DEFAULT (-(-9223372036854775808))
+  );
+  INSERT INTO t5 DEFAULT VALUES;
+}
+
+do_execsql_test alter4-9.2 { SELECT typeof(a), a, typeof(b), b FROM t5; } {
+  integer -9223372036854775808
+  real     9.22337203685478e+18
+}
+
+do_execsql_test alter4-9.3 { 
+  ALTER TABLE t5 ADD COLUMN c INTEGER DEFAULT (-(-9223372036854775808));
+  SELECT typeof(c), c FROM t5;
+} {real 9.22337203685478e+18}
+
 finish_test