diff --git a/internal/hammer/diff.go b/internal/hammer/diff.go
index d873cb3..9a55f71 100644
--- a/internal/hammer/diff.go
+++ b/internal/hammer/diff.go
@@ -403,7 +403,7 @@ func (g *Generator) generateDDLForColumns(from, to *Table) DDL {
 
 		if g.columnTypeEqual(fromCol, toCol) && fromCol.Generated == nil && toCol.Generated == nil {
 			if fromCol.Type.Base == spansql.Timestamp {
-				if fromCol.NotNull != toCol.NotNull {
+				if fromCol.NotNull != toCol.NotNull || !reflect.DeepEqual(fromCol.Default, toCol.Default) {
 					if !fromCol.NotNull && toCol.NotNull {
 						ddl.Append(Update{Table: to.Name, Def: toCol})
 					}
@@ -611,7 +611,12 @@ func (g *Generator) primaryKeyEqual(x, y *Table) bool {
 }
 
 func (g *Generator) columnDefEqual(x, y spansql.ColumnDef) bool {
-	return cmp.Equal(x, y, cmpopts.IgnoreTypes(spansql.Position{}))
+	return cmp.Equal(x, y,
+		cmpopts.IgnoreTypes(spansql.Position{}),
+		cmp.Comparer(func(x, y spansql.TimestampLiteral) bool {
+			return time.Time(x).Equal(time.Time(y))
+		}),
+	)
 }
 
 func (g *Generator) columnTypeEqual(x, y spansql.ColumnDef) bool {
diff --git a/internal/hammer/diff_test.go b/internal/hammer/diff_test.go
index 55ad7b2..f36a9f5 100644
--- a/internal/hammer/diff_test.go
+++ b/internal/hammer/diff_test.go
@@ -1361,6 +1361,25 @@ CREATE CHANGE STREAM SomeStream FOR ALL;
 			ignoreAlterDatabase: true,
 			expected:            []string{"ALTER CHANGE STREAM SomeStream SET OPTIONS (retention_period='1d', value_capture_type='OLD_AND_NEW_VALUES')"},
 		},
+		{
+			name: "both sides have identical fields of timestamp with a default value",
+			from: `
+CREATE TABLE Nonces (
+  nonce INT64 NOT NULL,
+  expires TIMESTAMP NOT NULL DEFAULT(TIMESTAMP '2000-01-01 00:00:00.000000+00:00'),
+) PRIMARY KEY(nonce);
+`,
+			to: `
+CREATE TABLE Nonces (
+  nonce INT64 NOT NULL,
+  expires TIMESTAMP NOT NULL DEFAULT(TIMESTAMP '2000-01-01 12:00:00.000000+00:00'),
+) PRIMARY KEY(nonce);
+`,
+			ignoreAlterDatabase: true,
+			expected: []string{
+				`ALTER TABLE Nonces ALTER COLUMN expires TIMESTAMP NOT NULL DEFAULT (TIMESTAMP '2000-01-01 12:00:00.000000+00:00')`,
+			},
+		},
 	}
 	for _, v := range values {
 		t.Run(v.name, func(t *testing.T) {