diff --git a/sqlit/domains/query/editing/clipboard.py b/sqlit/domains/query/editing/clipboard.py
index adb4c8e4..8040877b 100644
--- a/sqlit/domains/query/editing/clipboard.py
+++ b/sqlit/domains/query/editing/clipboard.py
@@ -27,6 +27,7 @@ def select_all_range(text: str) -> tuple[int, int, int, int]:
 
 def paste_text(text: str, row: int, col: int, clipboard: str) -> PasteResult:
     """Paste clipboard content at cursor position."""
+    clipboard = clipboard.replace("\r\n", "\n").replace("\r", "\n")
     lines = text.split("\n")
     if not lines:
         lines = [""]
diff --git a/sqlit/domains/query/ui/mixins/autocomplete.py b/sqlit/domains/query/ui/mixins/autocomplete.py
index b2d9ab35..cda9d6ab 100644
--- a/sqlit/domains/query/ui/mixins/autocomplete.py
+++ b/sqlit/domains/query/ui/mixins/autocomplete.py
@@ -88,20 +88,28 @@ def _apply_autocomplete(self: AutocompleteMixinHost) -> None:
     def _location_to_offset(self, text: str, location: tuple[int, int]) -> int:
         """Convert (row, col) location to text offset."""
         row, col = location
-        lines = text.split("\n")
-        offset = sum(len(lines[i]) + 1 for i in range(row))
-        offset += col
+        lines = text.splitlines(keepends=True)
+        offset = sum(len(line) for line in lines[:row]) + col
         return min(offset, len(text))
 
     def _offset_to_location(self, text: str, offset: int) -> tuple[int, int]:
         """Convert text offset to (row, col) location."""
-        lines = text.split("\n")
+        lines = text.splitlines(keepends=True)
+        if not lines:
+            return (0, 0)
+
         current_offset = 0
         for row, line in enumerate(lines):
-            if current_offset + len(line) >= offset:
+            content_length = len(line.rstrip("\r\n"))
+            if current_offset + content_length >= offset:
                 return (row, offset - current_offset)
-            current_offset += len(line) + 1
-        return (len(lines) - 1, len(lines[-1]) if lines else 0)
+            current_offset += len(line)
+            if offset < current_offset:
+                return (row, content_length)
+
+        if lines and lines[-1].endswith(("\r", "\n")):
+            return (len(lines), 0)
+        return (len(lines) - 1, len(lines[-1]))
 
     def on_text_area_changed(self: AutocompleteMixinHost, event: TextArea.Changed) -> None:
         """Handle text changes in the query editor for autocomplete."""
diff --git a/tests/unit/test_autocomplete_cursor_positions.py b/tests/unit/test_autocomplete_cursor_positions.py
new file mode 100644
index 00000000..5de1e4bc
--- /dev/null
+++ b/tests/unit/test_autocomplete_cursor_positions.py
@@ -0,0 +1,32 @@
+"""Tests for cursor position conversion used by autocomplete."""
+
+import pytest
+
+from sqlit.domains.query.ui.mixins.autocomplete import AutocompleteMixin
+
+
+@pytest.mark.parametrize("separator", ["\n", "\r\n", "\r"])
+def test_cursor_location_round_trip_for_line_endings(separator: str) -> None:
+    """Cursor conversion supports all common pasted-text line endings."""
+    lines = ["SELECT", "    column_name", "FROM users"]
+    text = separator.join(lines)
+    location = (2, 4)
+    expected_offset = len(lines[0]) + len(separator) + len(lines[1]) + len(separator) + location[1]
+
+    offset = AutocompleteMixin._location_to_offset(None, text, location)
+
+    assert offset == expected_offset
+    assert AutocompleteMixin._offset_to_location(None, text, offset) == location
+
+
+@pytest.mark.parametrize("separator", ["\n", "\r\n", "\r"])
+def test_offset_to_location_after_trailing_line_ending(separator: str) -> None:
+    """An offset after a trailing line ending maps to the next empty row."""
+    text = f"SELECT{separator}"
+
+    assert AutocompleteMixin._offset_to_location(None, text, len(text)) == (1, 0)
+
+
+def test_offset_to_location_for_empty_text() -> None:
+    """An empty editor starts at the first row and column."""
+    assert AutocompleteMixin._offset_to_location(None, "", 0) == (0, 0)
diff --git a/tests/unit/test_query_paste.py b/tests/unit/test_query_paste.py
new file mode 100644
index 00000000..3001f562
--- /dev/null
+++ b/tests/unit/test_query_paste.py
@@ -0,0 +1,15 @@
+"""Tests for pasting text into the query editor."""
+
+import pytest
+
+from sqlit.domains.query.editing import PasteResult, paste_text
+
+
+@pytest.mark.parametrize("separator", ["\n", "\r\n", "\r"])
+def test_paste_normalizes_line_endings(separator: str) -> None:
+    """Pasted queries use the line endings expected by editor operations."""
+    clipboard = separator.join(["SELECT", "FROM users"])
+
+    result = paste_text("", 0, 0, clipboard)
+
+    assert result == PasteResult("SELECT\nFROM users", 1, 10)