diff --git a/browser/installer/windows/nsis/installer.nsi b/browser/installer/windows/nsis/installer.nsi
index 24907e25f15af..9e51088ce108b 100644
--- a/browser/installer/windows/nsis/installer.nsi
+++ b/browser/installer/windows/nsis/installer.nsi
@@ -52,6 +52,7 @@ Var FinishPhaseStart
 Var FinishPhaseEnd
 Var InstallResult
 Var LaunchedNewApp
+Var PostSigningData
 
 ; By defining NO_STARTMENU_DIR an installer that doesn't provide an option for
 ; an application's Start Menu PROGRAMS directory and doesn't define the
@@ -98,6 +99,7 @@ VIAddVersionKey "OriginalFilename" "setup.exe"
 !insertmacro CheckForFilesInUse
 !insertmacro CleanUpdateDirectories
 !insertmacro CopyFilesFromDir
+!insertmacro CopyPostSigningData
 !insertmacro CreateRegKey
 !insertmacro GetFirstInstallPath
 !insertmacro GetLongPath
@@ -742,6 +744,23 @@ Section "-InstallEndCleanup"
   DetailPrint "$(STATUS_CLEANUP)"
   SetDetailsPrint none
 
+  ; Maybe copy the post-signing data?
+  StrCpy $PostSigningData ""
+  ${GetParameters} $0
+  ClearErrors
+  ; We don't get post-signing data from the MSI.
+  ${GetOptions} $0 "/LaunchedFromMSI" $1
+  ${If} ${Errors}
+    ; The stub will handle copying the data if it ran us.
+    ClearErrors
+    ${GetOptions} $0 "/LaunchedFromStub" $1
+    ${If} ${Errors}
+      ; We're being run standalone, copy the data.
+      ${CopyPostSigningData}
+      Pop $PostSigningData
+    ${EndIf}
+  ${EndIf}
+
   ${Unless} ${Silent}
     ClearErrors
     ${MUI_INSTALLOPTIONS_READ} $0 "summary.ini" "Field 4" "State"
@@ -1157,6 +1176,16 @@ Function SendPing
     nsJSON::Set /tree ping "Data" "finish_time" /value "$1"
   ${EndIf}
 
+  ; $PostSigningData should only be empty if we didn't try to copy the
+  ; postSigningData file at all. If we did try and the file was missing
+  ; or empty, this will be "0", and for consistency with the stub we will
+  ; still submit it.
+  ${If} $PostSigningData != ""
+    nsJSON::Quote /always $PostSigningData
+    Pop $0
+    nsJSON::Set /tree ping "Data" "attribution" /value $0
+  ${EndIf}
+
   nsJSON::Set /tree ping "Data" "new_launched" /value "$LaunchedNewApp"
 
   nsJSON::Set /tree ping "Data" "succeeded" /value false
diff --git a/browser/installer/windows/nsis/stub.nsi b/browser/installer/windows/nsis/stub.nsi
index cdc7ed1bbb621..1341f4dea6816 100644
--- a/browser/installer/windows/nsis/stub.nsi
+++ b/browser/installer/windows/nsis/stub.nsi
@@ -243,6 +243,7 @@ Var ArchToInstall
 
 !include "common.nsh"
 
+!insertmacro CopyPostSigningData
 !insertmacro ElevateUAC
 !insertmacro GetLongPath
 !insertmacro GetPathFromString
@@ -1287,7 +1288,9 @@ Function FinishInstall
 
   StrCpy $ExitCode "${ERR_SUCCESS}"
 
-  Call CopyPostSigningData
+  ${CopyPostSigningData}
+  Pop $PostSigningData
+
   Call LaunchApp
 FunctionEnd
 
@@ -1440,17 +1443,6 @@ Function WaitForAppLaunch
   ${EndIf}
 FunctionEnd
 
-Function CopyPostSigningData
-  ${LineRead} "$EXEDIR\postSigningData" "1" $PostSigningData
-  ${If} ${Errors}
-    ClearErrors
-    StrCpy $PostSigningData "0"
-  ${Else}
-    CreateDirectory "$LOCALAPPDATA\Mozilla\Firefox"
-    CopyFiles /SILENT "$EXEDIR\postSigningData" "$LOCALAPPDATA\Mozilla\Firefox"
-  ${Endif}
-FunctionEnd
-
 Function DisplayDownloadError
   WebBrowser::CancelTimer $TimerHandle
   ; To better display the error state on the taskbar set the progress completed
diff --git a/toolkit/mozapps/installer/windows/nsis/common.nsh b/toolkit/mozapps/installer/windows/nsis/common.nsh
index 663c728cf6536..941e0fc6e8691 100644
--- a/toolkit/mozapps/installer/windows/nsis/common.nsh
+++ b/toolkit/mozapps/installer/windows/nsis/common.nsh
@@ -7851,6 +7851,40 @@ end:
   !endif
 !macroend
 
+/**
+ * Copy the post-signing data, which was left alongside the installer
+ * by the self-extractor stub, into the global location for this data.
+ *
+ * If the post-signing data file doesn't exist, or is empty, "0" is
+ * pushed on the stack, and nothing is copied.
+ * Otherwise the first line of the post-signing data (including newline,
+ * if any) is pushed on the stack.
+ */
+!macro CopyPostSigningData
+  !ifndef ${_MOZFUNC_UN}CopyPostSigningData
+    !verbose push
+    !verbose ${_MOZFUNC_VERBOSE}
+    !define ${_MOZFUNC_UN}CopyPostSigningData "Call ${_MOZFUNC_UN}CopyPostSigningData"
+
+    Function CopyPostSigningData
+      Push $0   ; Stack: old $0
+
+      ${LineRead} "$EXEDIR\postSigningData" "1" $0
+      ${If} ${Errors}
+        ClearErrors
+        StrCpy $0 "0"
+      ${Else}
+        CreateDirectory "$LOCALAPPDATA\Mozilla\Firefox"
+        CopyFiles /SILENT "$EXEDIR\postSigningData" "$LOCALAPPDATA\Mozilla\Firefox"
+      ${Endif}
+
+      Exch $0   ; Stack: postSigningData
+    FunctionEnd
+
+    !verbose pop
+  !endif
+!macroend
+
 ################################################################################
 # Helpers for taskbar progress