diff --git a/src/buffer.hh b/src/buffer.hh
index c8870509..a7ab127c 100644
--- a/src/buffer.hh
+++ b/src/buffer.hh
@@ -102,10 +102,11 @@ public:
     enum class Flags
     {
         None = 0,
-        File = 1,
-        New  = 2,
-        Fifo = 4,
-        NoUndo = 8,
+        File   = 1 << 0,
+        New    = 1 << 1,
+        Fifo   = 1 << 2,
+        NoUndo = 1 << 3,
+        Debug  = 1 << 4
     };
 
     Buffer(String name, Flags flags, StringView data = {},
diff --git a/src/buffer_utils.cc b/src/buffer_utils.cc
index 5d1b6d5e..9a70a864 100644
--- a/src/buffer_utils.cc
+++ b/src/buffer_utils.cc
@@ -176,7 +176,7 @@ void write_to_debug_buffer(StringView str)
     else
     {
         String line = str + (eol_back ? "\n" : "\n\n");
-        new Buffer(debug_buffer_name.str(), Buffer::Flags::NoUndo, line, InvalidTime);
+        new Buffer(debug_buffer_name.str(), Buffer::Flags::NoUndo | Buffer::Flags::Debug, line, InvalidTime);
     }
 }
 
diff --git a/src/insert_completer.cc b/src/insert_completer.cc
index 27275363..c33673e6 100644
--- a/src/insert_completer.cc
+++ b/src/insert_completer.cc
@@ -124,7 +124,7 @@ InsertCompletion complete_word(const Buffer& buffer, ByteCoord cursor_pos, const
     {
         for (const auto& buf : BufferManager::instance())
         {
-            if (buf.get() == &buffer)
+            if (buf.get() == &buffer or buf->flags() & Buffer::Flags::Debug)
                 continue;
             add_matches(*buf);
         }