diff --git a/.github/actions/test-go-pg/action.yaml b/.github/actions/test-go-pg/action.yaml
index 5f19da6910822..bb646a5c05ad0 100644
--- a/.github/actions/test-go-pg/action.yaml
+++ b/.github/actions/test-go-pg/action.yaml
@@ -71,6 +71,7 @@ runs:
 
         if [[ ${RACE_DETECTION} == true ]]; then
           gotestsum --junitfile="gotests.xml" --packages="${TEST_PACKAGES}" -- \
+            -tags=testsmallbuffers \
             -race \
             -parallel "${TEST_NUM_PARALLEL_TESTS}" \
             -p "${TEST_NUM_PARALLEL_PACKAGES}"
diff --git a/Makefile b/Makefile
index 4997430f9dd1b..8f06f3f9ca09d 100644
--- a/Makefile
+++ b/Makefile
@@ -1018,7 +1018,8 @@ endif
 
 # default to 8x8 parallelism to avoid overwhelming our workspaces. Hopefully we can remove these defaults
 # when we get our test suite's resource utilization under control.
-GOTEST_FLAGS := -v -p $(or $(TEST_NUM_PARALLEL_PACKAGES),"8") -parallel=$(or $(TEST_NUM_PARALLEL_TESTS),"8")
+# Use testsmallbuffers tag to reduce wireguard memory allocation in tests (from ~18GB to negligible).
+GOTEST_FLAGS := -tags=testsmallbuffers -v -p $(or $(TEST_NUM_PARALLEL_PACKAGES),"8") -parallel=$(or $(TEST_NUM_PARALLEL_TESTS),"8")
 
 # The most common use is to set TEST_COUNT=1 to avoid Go's test cache.
 ifdef TEST_COUNT
@@ -1081,6 +1082,7 @@ test-postgres: test-postgres-docker
 		--jsonfile="gotests.json" \
 		$(GOTESTSUM_RETRY_FLAGS) \
 		--packages="./..." -- \
+		-tags=testsmallbuffers \
 		-timeout=20m \
 		-count=1
 .PHONY: test-postgres
@@ -1153,7 +1155,7 @@ test-postgres-docker:
 
 # Make sure to keep this in sync with test-go-race from .github/workflows/ci.yaml.
 test-race:
-	$(GIT_FLAGS) gotestsum --junitfile="gotests.xml" -- -race -count=1 -parallel 4 -p 4 ./...
+	$(GIT_FLAGS) gotestsum --junitfile="gotests.xml" -- -tags=testsmallbuffers -race -count=1 -parallel 4 -p 4 ./...
 .PHONY: test-race
 
 test-tailnet-integration:
@@ -1163,6 +1165,7 @@ test-tailnet-integration:
 		TS_DEBUG_NETCHECK=true \
 		GOTRACEBACK=single \
 		go test \
+			-tags=testsmallbuffers \
 			-exec "sudo -E" \
 			-timeout=5m \
 			-count=1 \
diff --git a/go.mod b/go.mod
index acc8abdba4fd8..5008b0a848528 100644
--- a/go.mod
+++ b/go.mod
@@ -41,7 +41,8 @@ replace tailscale.com => github.com/coder/tailscale v1.1.1-0.20250829055706-6eaf
 // This is replaced to include
 // 1. a fix for a data race: c.f. https://github.com/tailscale/wireguard-go/pull/25
 // 2. update to the latest gVisor
-replace github.com/tailscale/wireguard-go => github.com/coder/wireguard-go v0.0.0-20240522052547-769cdd7f7818
+// 3. testsmallbuffers build tag for reduced memory usage in tests
+replace github.com/tailscale/wireguard-go => github.com/coder/wireguard-go v0.0.0-20251212134302-bb12dfe22d7f
 
 // Switch to our fork that imports fixes from http://github.com/tailscale/ssh.
 // See: https://github.com/coder/coder/issues/3371
diff --git a/go.sum b/go.sum
index 9d226f7252c62..6630804b2ae6b 100644
--- a/go.sum
+++ b/go.sum
@@ -964,8 +964,8 @@ github.com/coder/websocket v1.8.13 h1:f3QZdXy7uGVz+4uCJy2nTZyM0yTBj8yANEHhqlXZ9F
 github.com/coder/websocket v1.8.13/go.mod h1:LNVeNrXQZfe5qhS9ALED3uA+l5pPqvwXg3CKoDBB2gs=
 github.com/coder/wgtunnel v0.1.13-0.20240522110300-ade90dfb2da0 h1:C2/eCr+r0a5Auuw3YOiSyLNHkdMtyCZHPFBx7syN4rk=
 github.com/coder/wgtunnel v0.1.13-0.20240522110300-ade90dfb2da0/go.mod h1:qANbdpqyAGlo2bg+4gQKPj24H1ZWa3bQU2Q5/bV5B3Y=
-github.com/coder/wireguard-go v0.0.0-20240522052547-769cdd7f7818 h1:bNhUTaKl3q0bFn78bBRq7iIwo72kNTvUD9Ll5TTzDDk=
-github.com/coder/wireguard-go v0.0.0-20240522052547-769cdd7f7818/go.mod h1:fAlLM6hUgnf4Sagxn2Uy5Us0PBgOYWz+63HwHUVGEbw=
+github.com/coder/wireguard-go v0.0.0-20251212134302-bb12dfe22d7f h1:EV5L4DiIuaoQNsM/9Ftm3C7mE2rr+PDf9ncGo+MqgeM=
+github.com/coder/wireguard-go v0.0.0-20251212134302-bb12dfe22d7f/go.mod h1:fAlLM6hUgnf4Sagxn2Uy5Us0PBgOYWz+63HwHUVGEbw=
 github.com/containerd/continuity v0.4.5 h1:ZRoN1sXq9u7V6QoHMcVWGhOwDFqZ4B9i5H6un1Wh0x4=
 github.com/containerd/continuity v0.4.5/go.mod h1:/lNJvtJKUQStBzpVQ1+rasXO1LAWtUQssk28EZvJ3nE=
 github.com/containerd/errdefs v1.0.0 h1:tg5yIfIlQIrxYtu9ajqY42W3lpS19XqdxRQeEwYG8PI=