diff --git a/pkg/merge/merge.go b/pkg/merge/merge.go
index 6a96180..6426688 100644
--- a/pkg/merge/merge.go
+++ b/pkg/merge/merge.go
@@ -492,7 +492,12 @@ func extractTypeParts(col *models.Column) (baseType string, length, precision, s
 		}
 	}
 
-	typeName = pgsql.NormalizePGType(typeName)
+	// serial/bigserial/smallserial are sugar over an integer column plus a
+	// sequence default; PostgreSQL itself reports the underlying integer
+	// type back for such columns, so treat them as equivalent here to avoid
+	// spurious conflicts between a DBML "bigserial" source and a live-read
+	// "bigint" target (or vice versa).
+	typeName = pgsql.SerialUnderlyingType(typeName)
 
 	return typeName, length, precision, scale
 }
diff --git a/pkg/merge/merge_test.go b/pkg/merge/merge_test.go
index e5f18cb..7b29805 100644
--- a/pkg/merge/merge_test.go
+++ b/pkg/merge/merge_test.go
@@ -196,6 +196,50 @@ func TestMergeColumns_TypeConflictIsDetected(t *testing.T) {
 	}
 }
 
+func TestMergeColumns_SerialVsUnderlyingIntegerIsNotAConflict(t *testing.T) {
+	target := &models.Database{
+		Schemas: []*models.Schema{
+			{
+				Name: "public",
+				Tables: []*models.Table{
+					{
+						Name:   "users",
+						Schema: "public",
+						Columns: map[string]*models.Column{
+							// As reported back by a live PostgreSQL read of an
+							// existing serial primary key column.
+							"id": {Name: "id", Type: "bigint"},
+						},
+					},
+				},
+			},
+		},
+	}
+	source := &models.Database{
+		Schemas: []*models.Schema{
+			{
+				Name: "public",
+				Tables: []*models.Table{
+					{
+						Name:   "users",
+						Schema: "public",
+						Columns: map[string]*models.Column{
+							// As declared in a DBML source spec.
+							"id": {Name: "id", Type: "bigserial"},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	result := MergeDatabases(target, source, nil)
+
+	if len(result.TypeConflicts) != 0 {
+		t.Fatalf("Expected no type conflicts for bigserial vs bigint, got %d: %+v", len(result.TypeConflicts), result.TypeConflicts)
+	}
+}
+
 func TestMergeConstraints_NewConstraint(t *testing.T) {
 	target := &models.Database{
 		Schemas: []*models.Schema{
diff --git a/pkg/pgsql/datatypes.go b/pkg/pgsql/datatypes.go
index cbdb380..de4fe19 100644
--- a/pkg/pgsql/datatypes.go
+++ b/pkg/pgsql/datatypes.go
@@ -193,6 +193,28 @@ func IsKnownPGBaseType(baseType string) bool {
 	return ok
 }
 
+// serialUnderlyingType maps each serial pseudo-type to the integer type
+// PostgreSQL actually stores the column as. serial/bigserial/smallserial are
+// not real types: they are sugar for an integer column plus a sequence
+// default, and pg_catalog (and information_schema) always reports the
+// underlying integer type back for such columns.
+var serialUnderlyingType = map[string]string{
+	"serial":      "integer",
+	"bigserial":   "bigint",
+	"smallserial": "smallint",
+}
+
+// SerialUnderlyingType returns the underlying integer type for a serial
+// pseudo-type (e.g. "bigserial" -> "bigint"). If baseType (after
+// NormalizePGType) is not a serial type, it is returned unchanged.
+func SerialUnderlyingType(baseType string) string {
+	normalized := NormalizePGType(baseType)
+	if underlying, ok := serialUnderlyingType[normalized]; ok {
+		return underlying
+	}
+	return normalized
+}
+
 func IsGoType(pTypeName string) bool {
 	for k := range GoToStdTypes {
 		if strings.EqualFold(pTypeName, k) {
diff --git a/pkg/writers/writer.go b/pkg/writers/writer.go
index 83b2a43..33f7e87 100644
--- a/pkg/writers/writer.go
+++ b/pkg/writers/writer.go
@@ -148,6 +148,26 @@ func SanitizeFilename(name string) string {
 // Examples (boolean):   "true"         → "true"
 // Examples (bigint):    "0"            → "0"
 // Examples (timestamp): "now()"        → "now()"   (function call – never quoted)
+// bareKeywordDefaults are PostgreSQL default-value keywords that are
+// expressions, not string literals, even though they contain no
+// parentheses (e.g. "CURRENT_DATE" rather than "now()"). They must never be
+// wrapped in quotes.
+var bareKeywordDefaults = map[string]bool{
+	"current_date":      true,
+	"current_time":      true,
+	"current_timestamp": true,
+	"localtime":         true,
+	"localtimestamp":    true,
+	"current_user":      true,
+	"session_user":      true,
+	"current_role":      true,
+	"current_catalog":   true,
+	"current_schema":    true,
+	"null":              true,
+	"true":              true,
+	"false":             true,
+}
+
 func QuoteDefaultValue(value, sqlType string) string {
 	value = strings.TrimSpace(value)
 
@@ -158,6 +178,12 @@ func QuoteDefaultValue(value, sqlType string) string {
 		return value
 	}
 
+	// Bare keyword expressions (e.g. CURRENT_DATE) are never quoted,
+	// regardless of column type.
+	if bareKeywordDefaults[strings.ToLower(value)] {
+		return value
+	}
+
 	// Normalise the SQL type: lowercase, strip length/precision suffix.
 	baseType := strings.ToLower(strings.TrimSpace(sqlType))
 	if idx := strings.Index(baseType, "("); idx > 0 {
diff --git a/pkg/writers/writer_test.go b/pkg/writers/writer_test.go
index 63a2830..a9548bb 100644
--- a/pkg/writers/writer_test.go
+++ b/pkg/writers/writer_test.go
@@ -41,6 +41,24 @@ func TestQuoteDefaultValue(t *testing.T) {
 			sqlType: "timestamptz",
 			want:    "now()",
 		},
+		{
+			name:    "bare keyword default CURRENT_DATE is not quoted",
+			value:   "CURRENT_DATE",
+			sqlType: "date",
+			want:    "CURRENT_DATE",
+		},
+		{
+			name:    "bare keyword default is case insensitive",
+			value:   "current_timestamp",
+			sqlType: "timestamptz",
+			want:    "current_timestamp",
+		},
+		{
+			name:    "bare keyword default localtime is not quoted",
+			value:   "LOCALTIME",
+			sqlType: "time",
+			want:    "LOCALTIME",
+		},
 	}
 
 	for _, tt := range tests {