diff --git a/kitty/data-types.h b/kitty/data-types.h
index 787452ff8..654766b7b 100644
--- a/kitty/data-types.h
+++ b/kitty/data-types.h
@@ -9,6 +9,7 @@
 
 #define PY_SSIZE_T_CLEAN
 #include <Python.h>
+#include <assert.h>
 #include <stdint.h>
 #include <stdbool.h>
 #include <poll.h>
@@ -163,12 +164,14 @@ typedef struct {
     sprite_index sprite_x, sprite_y, sprite_z;
     CellAttrs attrs;
 } GPUCell;
+static_assert(sizeof(GPUCell) == 20, "Fix the ordering of GPUCell");
 
 typedef struct {
     char_type ch;
-    combining_type cc_idx[2];
     hyperlink_id_type hyperlink_id;
+    combining_type cc_idx[3];
 } CPUCell;
+static_assert(sizeof(CPUCell) == 12, "Fix the ordering of CPUCell");
 
 typedef enum { UNKNOWN_PROMPT_KIND = 0, PROMPT_START = 1, SECONDARY_PROMPT = 2, OUTPUT_START = 3 } PromptKind;
 typedef union LineAttrs {
diff --git a/kitty_tests/datatypes.py b/kitty_tests/datatypes.py
index d0128868f..fd3d022c8 100644
--- a/kitty_tests/datatypes.py
+++ b/kitty_tests/datatypes.py
@@ -182,9 +182,11 @@ class TestDataTypes(BaseTest):
         l0.add_combining_char(0, '\U000e0100')
         self.ae(l0[0], ' \u0300\U000e0100')
         l0.add_combining_char(0, '\u0302')
-        self.ae(l0[0], ' \u0300\u0302')
+        self.ae(l0[0], ' \u0300\U000e0100\u0302')
+        l0.add_combining_char(0, '\u0301')
+        self.ae(l0[0], ' \u0300\U000e0100\u0301')
         self.ae(l0[1], '\0')
-        self.ae(str(l0), ' \u0300\u0302')
+        self.ae(str(l0), ' \u0300\U000e0100\u0301')
         t = 'Testing with simple text'
         lb = LineBuf(2, len(t))
         l0 = lb.line(0)