diff --git a/src/terminal/new/Terminal.zig b/src/terminal/new/Terminal.zig
index c9dc49bc6..d6d482822 100644
--- a/src/terminal/new/Terminal.zig
+++ b/src/terminal/new/Terminal.zig
@@ -1299,6 +1299,7 @@ pub fn insertBlanks(self: *Terminal, count: usize) void {
             // If the original source (now copied to dst) had graphemes,
             // we have to move them since they're stored by cell offset.
             if (dst.hasGrapheme()) {
+                assert(!src.hasGrapheme());
                 page.moveGraphemeWithinRow(src, dst);
             }
         }
@@ -1377,7 +1378,6 @@ fn blankCells(
         for (cells) |*cell| {
             if (cell.hasGrapheme()) page.clearGrapheme(row, cell);
         }
-        assert(!row.grapheme);
     }
 
     if (row.styled) {
@@ -4988,6 +4988,74 @@ test "Terminal: insertBlanks left/right scroll region large count" {
     }
 }
 
+test "Terminal: insertBlanks deleting graphemes" {
+    const alloc = testing.allocator;
+    var t = try init(alloc, 5, 5);
+    defer t.deinit(alloc);
+
+    // Disable grapheme clustering
+    t.modes.set(.grapheme_cluster, true);
+
+    try t.printString("ABC");
+
+    // This is: 👨‍👩‍👧 (which may or may not render correctly)
+    try t.print(0x1F468);
+    try t.print(0x200D);
+    try t.print(0x1F469);
+    try t.print(0x200D);
+    try t.print(0x1F467);
+
+    // We should have one cell with graphemes
+    const page = t.screen.cursor.page_offset.page.data;
+    try testing.expectEqual(@as(usize, 1), page.graphemeCount());
+
+    t.setCursorPos(1, 1);
+    t.insertBlanks(4);
+
+    {
+        const str = try t.plainString(testing.allocator);
+        defer testing.allocator.free(str);
+        try testing.expectEqualStrings("    A", str);
+    }
+
+    // We should have no graphemes
+    try testing.expectEqual(@as(usize, 0), page.graphemeCount());
+}
+
+test "Terminal: insertBlanks shift graphemes" {
+    const alloc = testing.allocator;
+    var t = try init(alloc, 5, 5);
+    defer t.deinit(alloc);
+
+    // Disable grapheme clustering
+    t.modes.set(.grapheme_cluster, true);
+
+    try t.printString("A");
+
+    // This is: 👨‍👩‍👧 (which may or may not render correctly)
+    try t.print(0x1F468);
+    try t.print(0x200D);
+    try t.print(0x1F469);
+    try t.print(0x200D);
+    try t.print(0x1F467);
+
+    // We should have one cell with graphemes
+    const page = t.screen.cursor.page_offset.page.data;
+    try testing.expectEqual(@as(usize, 1), page.graphemeCount());
+
+    t.setCursorPos(1, 1);
+    t.insertBlanks(1);
+
+    {
+        const str = try t.plainString(testing.allocator);
+        defer testing.allocator.free(str);
+        try testing.expectEqualStrings(" A👨‍👩‍👧", str);
+    }
+
+    // We should have no graphemes
+    try testing.expectEqual(@as(usize, 1), page.graphemeCount());
+}
+
 test "Terminal: insert mode with space" {
     const alloc = testing.allocator;
     var t = try init(alloc, 10, 2);
diff --git a/src/terminal/new/page.zig b/src/terminal/new/page.zig
index c799ee4c6..adc475264 100644
--- a/src/terminal/new/page.zig
+++ b/src/terminal/new/page.zig
@@ -321,11 +321,30 @@ pub const Page = struct {
         row.grapheme = false;
     }
 
+    /// Returns the number of graphemes in the page. This isn't the byte
+    /// size but the total number of unique cells that have grapheme data.
+    pub fn graphemeCount(self: *const Page) usize {
+        return self.grapheme_map.map(self.memory).count();
+    }
+
     /// Move graphemes to another cell in the same row.
     pub fn moveGraphemeWithinRow(self: *Page, src: *Cell, dst: *Cell) void {
-        _ = self;
-        _ = src;
-        _ = dst;
+        // Note: we don't assert src has graphemes here because one of
+        // the places we call this is from insertBlanks where the cells have
+        // already swapped cell data but not grapheme data.
+
+        // Get our entry in the map, which must exist
+        const src_offset = getOffset(Cell, self.memory, src);
+        var map = self.grapheme_map.map(self.memory);
+        const entry = map.getEntry(src_offset).?;
+        const value = entry.value_ptr.*;
+
+        // Remove the entry so we know we have space
+        map.removeByPtr(entry.key_ptr);
+
+        // Add the entry for the new cell
+        const dst_offset = getOffset(Cell, self.memory, dst);
+        map.putAssumeCapacity(dst_offset, value);
     }
 
     pub const Layout = struct {