diff --git a/firmware/font.c b/firmware/font.c
index 2be90355db..e6f90e4ca5 100644
--- a/firmware/font.c
+++ b/firmware/font.c
@@ -93,8 +93,10 @@ static int buflibmove_callback(int handle, void* current, void* new)
     if (alloc->handle_locked)
         return BUFLIB_CB_CANNOT_MOVE;
 
-    alloc->font.bits += diff;
-    alloc->font.offset += diff;
+    if (alloc->font.bits)
+        alloc->font.bits += diff;
+    if (alloc->font.offset)
+        alloc->font.offset += diff;
     if (alloc->font.width)
         alloc->font.width += diff;
 
@@ -102,8 +104,10 @@ static int buflibmove_callback(int handle, void* current, void* new)
     alloc->font.buffer_end += diff;
     alloc->font.buffer_position += diff;
 
-    alloc->font.cache._index += diff;
-    alloc->font.cache._lru._base += diff;
+    if (alloc->font.cache._index)
+        alloc->font.cache._index += diff;
+    if (alloc->font.cache._lru._base)
+        alloc->font.cache._lru._base += diff;
 
     return BUFLIB_CB_OK;
 }