diff --git a/py/makeqstrdata.py b/py/makeqstrdata.py
index 5b5ec1c37..8e3835d86 100644
--- a/py/makeqstrdata.py
+++ b/py/makeqstrdata.py
@@ -180,7 +180,7 @@ def compress(encoding_table, decompressed):
     if not isinstance(decompressed, bytes):
         raise TypeError()
     values, lengths = encoding_table
-    enc = bytearray(len(decompressed))
+    enc = bytearray(len(decompressed) * 2)
     #print(decompressed)
     #print(lengths)
     current_bit = 7
@@ -227,6 +227,8 @@ def compress(encoding_table, decompressed):
                 current_bit -= 1
     if current_bit != 7:
         current_byte += 1
+    if current_byte > len(decompressed):
+        print("Note: compression increased length", repr(decompressed.decode('utf-8')), len(decompressed), current_byte, file=sys.stderr)
     return enc[:current_byte]
 
 def qstr_escape(qst):