diff --git a/cmd/cigocacher/cigocacher.go b/cmd/cigocacher/cigocacher.go
index 74ed08367..e541403a1 100644
--- a/cmd/cigocacher/cigocacher.go
+++ b/cmd/cigocacher/cigocacher.go
@@ -143,19 +143,26 @@ func main() {
 			log.Printf("Using cigocached at %s", *srvURL)
 		}
 		c.remote = &cachers.HTTPClient{
-			BaseURL:        *srvURL,
-			Disk:           c.disk,
-			HTTPClient:     httpClient(srvHost, *srvHostDial),
-			AccessToken:    *token,
-			Verbose:        *verbose,
-			BestEffortHTTP: true,
+			BaseURL:               *srvURL,
+			Disk:                  c.disk,
+			HTTPClient:            httpClient(srvHost, *srvHostDial),
+			AccessToken:           *token,
+			Verbose:               *verbose,
+			BestEffortHTTP:        true,
+			AsyncPutTimeout:       10 * time.Second, // Generous enough to allow for big objects ~100MiB.
+			AsyncPutMaxConcurrent: 10,
 		}
 	}
 	var p *cacheproc.Process
 	p = &cacheproc.Process{
 		Close: func() error {
+			if c.remote != nil {
+				if !c.remote.Shutdown() {
+					log.Printf("cigocacher: timed out waiting for background PUTs to drain")
+				}
+			}
 			if c.verbose {
-				log.Printf("gocacheprog: closing; %d gets (%d hits, %d misses, %d errors); %d puts (%d errors)",
+				log.Printf("cigocacher: closing; %d gets (%d hits, %d misses, %d errors); %d puts (%d errors)",
 					p.Gets.Load(), p.GetHits.Load(), p.GetMisses.Load(), p.GetErrors.Load(), p.Puts.Load(), p.PutErrors.Load())
 			}
 			return c.close()
diff --git a/flake.nix b/flake.nix
index a08042da2..875d3f359 100644
--- a/flake.nix
+++ b/flake.nix
@@ -173,4 +173,4 @@
     });
   };
 }
-# nix-direnv cache busting line: sha256-7+zxTSp/uFcWHbZPqmffTzNUjCiwdKouAjqL1U5TV5k=
+# nix-direnv cache busting line: sha256-amKkUPszyhG4N5ZtrB01swBACYq76raSS+SQRneLmwc=
diff --git a/flakehashes.json b/flakehashes.json
index ef03f12ea..1a4f1a40c 100644
--- a/flakehashes.json
+++ b/flakehashes.json
@@ -4,7 +4,7 @@
     "sri": "sha256-TwIaPmGVHO9ZwdaO/jDStgWGQtKa4smS3er1i5aTNTw="
   },
   "vendor": {
-    "goModSum": "sha256-3KQ4C93byCm5ioPVBi+GC8mwonqhsdBdpBhUWTCZyoM=",
-    "sri": "sha256-7+zxTSp/uFcWHbZPqmffTzNUjCiwdKouAjqL1U5TV5k="
+    "goModSum": "sha256-AbvfXWjfcRZHLJOp2Vuslvie8ROmm2pGvhxYIs07aNY=",
+    "sri": "sha256-amKkUPszyhG4N5ZtrB01swBACYq76raSS+SQRneLmwc="
   }
 }
diff --git a/go.mod b/go.mod
index 81bb6cc9b..9c0e45c81 100644
--- a/go.mod
+++ b/go.mod
@@ -17,7 +17,7 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/s3 v1.75.3
 	github.com/aws/aws-sdk-go-v2/service/ssm v1.45.0
 	github.com/axiomhq/hyperloglog v0.0.0-20240319100328-84253e514e02
-	github.com/bradfitz/go-tool-cache v0.0.0-20260216153636-9e5201344fe5
+	github.com/bradfitz/go-tool-cache v0.0.0-20260722201841-0bb331e19f64
 	github.com/bradfitz/monogok v0.0.0-20260630033929-b1eef977b41f
 	github.com/bradfitz/qemu-guest-kragent v0.0.0-20240513123539-55a43ea02a03
 	github.com/bramvdbogaerde/go-scp v1.4.0
diff --git a/go.sum b/go.sum
index 297fa3390..ac10645a1 100644
--- a/go.sum
+++ b/go.sum
@@ -211,8 +211,8 @@ github.com/boltdb/bolt v1.3.1 h1:JQmyP4ZBrce+ZQu0dY660FMfatumYDLun9hBCUVIkF4=
 github.com/boltdb/bolt v1.3.1/go.mod h1:clJnj/oiGkjum5o1McbSZDSLxVThjynRyGBgiAx27Ps=
 github.com/bombsimon/wsl/v4 v4.2.1 h1:Cxg6u+XDWff75SIFFmNsqnIOgob+Q9hG6y/ioKbRFiM=
 github.com/bombsimon/wsl/v4 v4.2.1/go.mod h1:Xu/kDxGZTofQcDGCtQe9KCzhHphIe0fDuyWTxER9Feo=
-github.com/bradfitz/go-tool-cache v0.0.0-20260216153636-9e5201344fe5 h1:0sG3c7afYdBNlc3QyhckvZ4bV9iqlfqCQM1i+mWm0eE=
-github.com/bradfitz/go-tool-cache v0.0.0-20260216153636-9e5201344fe5/go.mod h1:78ZLITnBUCDJeU01+wYYJKaPYYgsDzJPRfxeI8qFh5g=
+github.com/bradfitz/go-tool-cache v0.0.0-20260722201841-0bb331e19f64 h1:4FMo2ozvaa8GQNXf66C+jXzLh6gNudUtT84uuHGm09k=
+github.com/bradfitz/go-tool-cache v0.0.0-20260722201841-0bb331e19f64/go.mod h1:n1IcQ3NLdg7hL0XnSuQpkbHG0W+gYAgKoru/Y/WZaEY=
 github.com/bradfitz/monogok v0.0.0-20260630033929-b1eef977b41f h1:voy0korWbg2e1gsJpBZ8/OBhVL8evXeUwbCZcA1PWv8=
 github.com/bradfitz/monogok v0.0.0-20260630033929-b1eef977b41f/go.mod h1:TG1HbU9fRVDnNgXncVkKz9GdvjIvqquXjH6QZSEVmY4=
 github.com/bradfitz/qemu-guest-kragent v0.0.0-20240513123539-55a43ea02a03 h1:V1gD/xbQZtimHXZ0y19oMgTVBIXQyazG/mG9JIflrIY=
diff --git a/shell.nix b/shell.nix
index 0dec1dc2d..e12f398bc 100644
--- a/shell.nix
+++ b/shell.nix
@@ -16,4 +16,4 @@
 ) {
   src =  ./.;
 }).shellNix
-# nix-direnv cache busting line: sha256-7+zxTSp/uFcWHbZPqmffTzNUjCiwdKouAjqL1U5TV5k=
+# nix-direnv cache busting line: sha256-amKkUPszyhG4N5ZtrB01swBACYq76raSS+SQRneLmwc=