diff --git a/src/display_buffer.cc b/src/display_buffer.cc
index 0865211a..8a8eb09e 100644
--- a/src/display_buffer.cc
+++ b/src/display_buffer.cc
@@ -12,6 +12,7 @@ DisplayBuffer::DisplayBuffer()
 DisplayBuffer::iterator DisplayBuffer::split(iterator atom, size_t pos_in_atom)
 {
     assert(atom < end());
+    assert(pos_in_atom > 0);
     assert(pos_in_atom < atom->content.length());
     DisplayAtom new_atom(atom->begin, atom->begin + pos_in_atom,
                          atom->content.substr(0, pos_in_atom),
diff --git a/src/window.cc b/src/window.cc
index 122767ee..2ba97048 100644
--- a/src/window.cc
+++ b/src/window.cc
@@ -114,7 +114,9 @@ static void blink_void(DisplayBuffer& display_buffer)
         size_t pos = atom_it->content.find("void");
         if (pos != std::string::npos)
         {
-            atom_it = display_buffer.split(atom_it, pos) + 1;
+            if (pos != 0)
+                atom_it = display_buffer.split(atom_it, pos) + 1;
+
             atom_it = display_buffer.split(atom_it, 4);
             atom_it->attribute |= Attributes::Blink;
             ++atom_it;