diff --git a/refinery/units/compression/decompress.py b/refinery/units/compression/decompress.py
index 43a0913da8..74e2529811 100644
--- a/refinery/units/compression/decompress.py
+++ b/refinery/units/compression/decompress.py
@@ -118,7 +118,7 @@ def decompress(engine: Unit, cutoff: int = 0, prefix: Optional[int] = None):
             if engine.handles(ingest) is False:
                 return Decompression(engine, None, cutoff, prefix)
             try:
-                result = engine.process(ingest)
+                result = next(engine.act(ingest))
             except RefineryPartialResult as pr:
                 result = pr.partial
             except Exception:
diff --git a/refinery/units/compression/zl.py b/refinery/units/compression/zl.py
index 1588a89cca..753de32f47 100644
--- a/refinery/units/compression/zl.py
+++ b/refinery/units/compression/zl.py
@@ -1,8 +1,10 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 import zlib
+import itertools
 
-from refinery.units import Arg, Unit
+from refinery.units import Arg, Unit, RefineryPartialResult
+from refinery.lib.tools import exception_to_string
 
 
 class zl(Unit):
@@ -14,40 +16,64 @@ def __init__(
         self,
         level  : Arg.Number('-l', bound=(0, 0X9), help='Specify a compression level between 0 and 9.') = 9,
         window : Arg.Number('-w', bound=(8, 0XF), help='Manually specify the window size between 8 and 15.') = 15,
-        force  : Arg.Switch('-f', help='Decompress as far as possible, even if all known methods fail.') = False,
         zlib_header: Arg.Switch('-z', group='MODE', help='Use a ZLIB header.') = False,
         gzip_header: Arg.Switch('-g', group='MODE', help='Use a GZIP header.') = False
     ):
         if zlib_header and gzip_header:
             raise ValueError('You can only specify one header type (ZLIB or GZIP).')
-        return super().__init__(level=level, window=window, force=force, zlib_header=zlib_header, gzip_header=gzip_header)
+        return super().__init__(level=level, window=window, zlib_header=zlib_header, gzip_header=gzip_header)
 
-    def _force_decompress(self, data, mode):
-        z = zlib.decompressobj(mode)
-
-        def as_many_as_possible():
-            for k in range(len(data)):
-                try: yield z.decompress(data[k : k + 1])
-                except zlib.error: break
-
-        return B''.join(as_many_as_possible())
+    def _decompress_data(self, data, mode: int, step: int):
+        zl = zlib.decompressobj(mode)
+        memory = memoryview(data)
+        result = bytearray()
+        while not zl.eof:
+            read = min(step, len(memory))
+            try:
+                chunk = zl.decompress(memory[:read])
+            except zlib.error as e:
+                raise RefineryPartialResult(exception_to_string(e), result) from e
+            else:
+                result.extend(chunk)
+                consumed = read - len(zl.unused_data)
+                if not memory or consumed == 0:
+                    break
+                memory = memory[consumed:]
+        return result, memory
 
     def process(self, data):
         if data[0] == 0x78 or data[0:2] == B'\x1F\x8B' or self.args.zlib_header or self.args.gzip_header:
-            mode_candidates = [self.args.window | 0x20, -self.args.window]
+            modes = [self.args.window | 0x20, -self.args.window]
         else:
-            mode_candidates = [-self.args.window, self.args.window | 0x20]
-        mode_candidates.extend([0x10 | self.args.window, 0])
-        for mode in mode_candidates:
-            self.log_debug(F'using mode {mode} for decompression')
-            try:
-                z = zlib.decompressobj(mode)
-                return z.decompress(data)
-            except zlib.error:
-                pass
-        if self.args.force:
-            return self._force_decompress(data, mode_candidates[0])
-        raise ValueError('could not detect any zlib stream.')
+            modes = [-self.args.window, self.args.window | 0x20]
+        modes.extend([0x10 | self.args.window, 0])
+        view = memoryview(data)
+        step = 32 if self.args.lenient else len(data)
+        for k in itertools.count(1):
+            error = None
+            rest = view
+            for mode in modes:
+                try:
+                    out, rest = self._decompress_data(view, mode, step)
+                except Exception as e:
+                    error = error or e
+                else:
+                    self.log_info(F'used mode {mode} to decompress chunk {k}')
+                    yield out
+                    error = None
+                    break
+            if error:
+                raise error
+            if not rest:
+                break
+            if len(rest) == len(view):
+                break
+            if len(rest) > len(view):
+                raise RuntimeError('Decompressor returned more tail data than input data.')
+            yield out
+            view = rest
+        if k <= 0:
+            raise ValueError('Could not detect any zlib stream.')
 
     def reverse(self, data):
         mode = -self.args.window