diff --git a/alembic/versions/d3e4f5a6b7c8_expand_oauth_url_columns.py b/alembic/versions/d3e4f5a6b7c8_expand_oauth_url_columns.py
new file mode 100644
index 0000000..58a0437
--- /dev/null
+++ b/alembic/versions/d3e4f5a6b7c8_expand_oauth_url_columns.py
@@ -0,0 +1,50 @@
+"""expand-oauth-url-columns
+
+Increase profile_url and image_url in oauth_connection to unbounded Unicode
+(TEXT) to accommodate OAuth providers that return URLs longer than 512 chars.
+
+Revision ID: d3e4f5a6b7c8
+Revises: c2d3e4f5a6b7
+Create Date: 2026-05-13 00:00:00.000000
+
+"""
+
+import sqlalchemy as sa
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = "d3e4f5a6b7c8"
+down_revision = "c2d3e4f5a6b7"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.alter_column(
+        "oauth_connection",
+        "profile_url",
+        type_=sa.Unicode(2048),
+        existing_type=sa.Unicode(512),
+    )
+    op.alter_column(
+        "oauth_connection",
+        "image_url",
+        type_=sa.Unicode(2048),
+        existing_type=sa.Unicode(512),
+    )
+
+
+def downgrade() -> None:
+    op.alter_column(
+        "oauth_connection",
+        "image_url",
+        type_=sa.Unicode(512),
+        existing_type=sa.Unicode(2048),
+    )
+    op.alter_column(
+        "oauth_connection",
+        "profile_url",
+        type_=sa.Unicode(512),
+        existing_type=sa.Unicode(2048),
+    )
diff --git a/src/powonline/model.py b/src/powonline/model.py
index 0383970..6aad532 100644
--- a/src/powonline/model.py
+++ b/src/powonline/model.py
@@ -401,8 +401,8 @@ class OauthConnection(Base, TimestampMixin):  # type: ignore
     access_token: Mapped[str | None] = mapped_column(Unicode(255))
     secret: Mapped[str | None] = mapped_column(Unicode(255))
     display_name: Mapped[str | None] = mapped_column(Unicode(255))
-    profile_url: Mapped[str | None] = mapped_column(Unicode(512))
-    image_url: Mapped[str | None] = mapped_column(Unicode(512))
+    profile_url: Mapped[str | None] = mapped_column(Unicode(2048))
+    image_url: Mapped[str | None] = mapped_column(Unicode(2048))
     rank: Mapped[int | None] = mapped_column()
 
     user: Mapped["User"] = relationship(