diff --git a/server/fishtest/rundb.py b/server/fishtest/rundb.py
index 7c46d32a9..b8277ee95 100644
--- a/server/fishtest/rundb.py
+++ b/server/fishtest/rundb.py
@@ -89,11 +89,12 @@ def __init__(self, generator):
     def read(self, size=-1):
         while size < 0 or len(self.buffer) < size:
             try:
-                self.buffer += next(self.generator)
+                chunk = next(self.generator)
+                self.buffer += chunk
+                result, self.buffer = self.buffer[:size], self.buffer[size:]
+                yield result
             except StopIteration:
                 break
-        result, self.buffer = self.buffer[:size], self.buffer[size:]
-        return result
 
     def close(self):
         pass  # No cleanup needed, but method is required