diff --git a/datamind/capabilities/db/base.py b/datamind/capabilities/db/base.py
index d0bfeab..0ebfc32 100644
--- a/datamind/capabilities/db/base.py
+++ b/datamind/capabilities/db/base.py
@@ -106,6 +106,8 @@ async def execute_readonly(
     ) -> QueryResult:
         if not sql or not sql.strip():
             raise CapabilityError("db", "Empty SQL")
+        if row_limit < 1:
+            raise CapabilityError("db", "row_limit must be at least 1")
         if contains_multiple_statements(sql):
             raise MultiStatementSQLError(
                 "multiple statements are not allowed (use a single SELECT)"
diff --git a/datamind/config.py b/datamind/config.py
index ea512e1..b251a26 100644
--- a/datamind/config.py
+++ b/datamind/config.py
@@ -112,7 +112,7 @@ class DBConfig(BaseModel):
     dialect: str = "sqlite"  # sqlite | mysql | postgres | ...
     dsn: str | None = None   # e.g. mysql+pymysql://user:pw@host/db
     read_only: bool = True
-    row_limit: int = 1000
+    row_limit: int = Field(default=1000, ge=1)
     query_timeout_s: float = 10.0
 
 
diff --git a/datamind/tests/test_config.py b/datamind/tests/test_config.py
index 8dda7ea..11743ed 100644
--- a/datamind/tests/test_config.py
+++ b/datamind/tests/test_config.py
@@ -14,7 +14,7 @@
 import pytest
 from pydantic import ValidationError
 
-from datamind.config import Settings
+from datamind.config import DBConfig, Settings
 
 
 def test_nested_env_hydrates_required_llm(monkeypatch, tmp_path):
@@ -101,3 +101,8 @@ def test_ensure_dirs_is_idempotent(monkeypatch, tmp_path):
 
     assert (tmp_path / "data" / "profiles" / "tp").is_dir()
     assert (tmp_path / "storage" / "tp").is_dir()
+
+
+def test_db_config_rejects_nonpositive_row_limit():
+    with pytest.raises(ValidationError):
+        DBConfig(row_limit=0)
diff --git a/datamind/tests/test_db_safeguard.py b/datamind/tests/test_db_safeguard.py
index bda0bd6..874043f 100644
--- a/datamind/tests/test_db_safeguard.py
+++ b/datamind/tests/test_db_safeguard.py
@@ -12,6 +12,8 @@
     leading_verb,
     strip_comments,
 )
+from datamind.capabilities.db.providers.sqlite import SQLiteDialect
+from datamind.core.errors import CapabilityError
 
 
 @pytest.mark.parametrize(
@@ -67,3 +69,17 @@ def test_ensure_row_limit_strips_trailing_semicolon():
 def test_strip_comments():
     assert strip_comments("SELECT /* x */ 1") == "SELECT  1"
     assert strip_comments("-- line\nSELECT 1") == "\nSELECT 1"
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("row_limit", [0, -1])
+async def test_execute_readonly_rejects_nonpositive_row_limit(tmp_path, row_limit):
+    dialect = SQLiteDialect()
+    engine = dialect.build_engine(
+        None, default_path=str(tmp_path / "db.sqlite")
+    )
+
+    with pytest.raises(CapabilityError, match="row_limit"):
+        await dialect.execute_readonly(
+            engine, "SELECT 1", row_limit=row_limit
+        )