diff --git a/cmd/tailscaled/tailscaled_windows.go b/cmd/tailscaled/tailscaled_windows.go
index bf1973caa..d916cc629 100644
--- a/cmd/tailscaled/tailscaled_windows.go
+++ b/cmd/tailscaled/tailscaled_windows.go
@@ -131,7 +131,7 @@ func isWindowsService() bool {
 // Windows started.
 func runWindowsService(pol *logpolicy.Policy) error {
 	go func() {
-		osdiag.LogSupportInfo(logger.WithPrefix(log.Printf, "Support Info: "), osdiag.LogSupportInfoReasonStartup)
+		logger.Logf(log.Printf).JSON(1, "SupportInfo", osdiag.SupportInfo(osdiag.LogSupportInfoReasonStartup))
 	}()
 
 	if logSCMInteractions, _ := syspolicy.GetBoolean(syspolicy.LogSCMInteractions, false); logSCMInteractions {
diff --git a/ipn/localapi/localapi.go b/ipn/localapi/localapi.go
index 44a840c01..7f70dadee 100644
--- a/ipn/localapi/localapi.go
+++ b/ipn/localapi/localapi.go
@@ -380,7 +380,7 @@ func (h *Handler) serveBugReport(w http.ResponseWriter, r *http.Request) {
 	envknob.LogCurrent(logger.WithPrefix(h.logf, "user bugreport: "))
 
 	// OS-specific details
-	osdiag.LogSupportInfo(logger.WithPrefix(h.logf, "user bugreport OS: "), osdiag.LogSupportInfoReasonBugReport)
+	h.logf.JSON(1, "UserBugReportOS", osdiag.SupportInfo(osdiag.LogSupportInfoReasonBugReport))
 
 	if defBool(r.URL.Query().Get("diagnose"), false) {
 		h.b.Doctor(r.Context(), logger.WithPrefix(h.logf, "diag: "))
diff --git a/util/osdiag/osdiag.go b/util/osdiag/osdiag.go
index df1bcb362..2ebecbdbf 100644
--- a/util/osdiag/osdiag.go
+++ b/util/osdiag/osdiag.go
@@ -4,8 +4,6 @@
 // Package osdiag provides loggers for OS-specific diagnostic information.
 package osdiag
 
-import "tailscale.com/types/logger"
-
 // LogSupportInfoReason is an enumeration indicating the reason for logging
 // support info.
 type LogSupportInfoReason int
@@ -15,9 +13,8 @@
 	LogSupportInfoReasonBugReport                                 // a bugreport is in the process of being gathered.
 )
 
-// LogSupportInfo obtains OS-specific diagnostic information useful for
-// troubleshooting and support, and writes it to logf. The reason argument is
-// useful for governing the verbosity of this function's output.
-func LogSupportInfo(logf logger.Logf, reason LogSupportInfoReason) {
-	logSupportInfo(logf, reason)
+// SupportInfo obtains OS-specific diagnostic information for troubleshooting
+// and support. The reason governs the verbosity of the output.
+func SupportInfo(reason LogSupportInfoReason) map[string]any {
+	return supportInfo(reason)
 }
diff --git a/util/osdiag/osdiag_notwindows.go b/util/osdiag/osdiag_notwindows.go
index da172b967..0e46c97e5 100644
--- a/util/osdiag/osdiag_notwindows.go
+++ b/util/osdiag/osdiag_notwindows.go
@@ -5,7 +5,6 @@
 
 package osdiag
 
-import "tailscale.com/types/logger"
-
-func logSupportInfo(logger.Logf, LogSupportInfoReason) {
+func supportInfo(LogSupportInfoReason) map[string]any {
+	return nil
 }
diff --git a/util/osdiag/osdiag_windows.go b/util/osdiag/osdiag_windows.go
index beb1bc26a..5dcce3bea 100644
--- a/util/osdiag/osdiag_windows.go
+++ b/util/osdiag/osdiag_windows.go
@@ -5,10 +5,8 @@
 
 import (
 	"encoding/binary"
-	"encoding/json"
 	"errors"
 	"fmt"
-	"io"
 	"path/filepath"
 	"strings"
 	"unicode/utf16"
@@ -18,7 +16,6 @@
 	"github.com/dblohm7/wingoes/pe"
 	"golang.org/x/sys/windows"
 	"golang.org/x/sys/windows/registry"
-	"tailscale.com/types/logger"
 	"tailscale.com/util/osdiag/internal/wsc"
 	"tailscale.com/util/winutil"
 	"tailscale.com/util/winutil/authenticode"
@@ -34,15 +31,6 @@
 	initialValueBufLen = 80    // large enough to contain a stringified GUID encoded as UTF-16
 )
 
-func logSupportInfo(logf logger.Logf, reason LogSupportInfoReason) {
-	var b strings.Builder
-	if err := getSupportInfo(&b, reason); err != nil {
-		logf("error encoding support info: %v", err)
-		return
-	}
-	logf("%s", b.String())
-}
-
 const (
 	supportInfoKeyModules    = "modules"
 	supportInfoKeyPageFile   = "pageFile"
@@ -51,7 +39,7 @@ func logSupportInfo(logf logger.Logf, reason LogSupportInfoReason) {
 	supportInfoKeyWinsockLSP = "winsockLSP"
 )
 
-func getSupportInfo(w io.Writer, reason LogSupportInfoReason) error {
+func supportInfo(reason LogSupportInfoReason) map[string]any {
 	output := make(map[string]any)
 
 	regInfo, err := getRegistrySupportInfo(registry.LOCAL_MACHINE, []string{winutil.RegPolicyBase, winutil.RegBase})
@@ -86,8 +74,7 @@ func getSupportInfo(w io.Writer, reason LogSupportInfoReason) error {
 		}
 	}
 
-	enc := json.NewEncoder(w)
-	return enc.Encode(output)
+	return output
 }
 
 type getRegistrySupportInfoBufs struct {