diff --git a/src/windows/installer-translations/english.nsi b/src/windows/installer-translations/english.nsi
index cfbe4c57e..1cad50928 100644
--- a/src/windows/installer-translations/english.nsi
+++ b/src/windows/installer-translations/english.nsi
@@ -12,6 +12,8 @@ LangString inst_torrent ${LANG_ENGLISH} "Open .torrent files with qBittorrent"
 LangString inst_magnet ${LANG_ENGLISH} "Open magnet links with qBittorrent"
 ;LangString inst_firewall ${LANG_ENGLISH} "Add Windows Firewall rule"
 LangString inst_firewall ${LANG_ENGLISH} "Add Windows Firewall rule"
+;LangString inst_warning ${LANG_ENGLISH} "qBittorrent is running. Please close the application before installing."
+LangString inst_warning ${LANG_ENGLISH} "qBittorrent is running. Please close the application before installing."
 
 
 ;------------------------------------
@@ -31,3 +33,5 @@ LangString remove_conf ${LANG_ENGLISH} "Remove configuration files"
 LangString remove_firewall ${LANG_ENGLISH} "Remove Windows Firewall rule"
 ;LangString remove_cache ${LANG_ENGLISH} "Remove torrents and cached data"
 LangString remove_cache ${LANG_ENGLISH} "Remove torrents and cached data"
+;LangString uninst_warning ${LANG_ENGLISH} "qBittorrent is running. Please close the application before uninstalling."
+LangString uninst_warning ${LANG_ENGLISH} "qBittorrent is running. Please close the application before uninstalling."
diff --git a/src/windows/installer.nsi b/src/windows/installer.nsi
index 4db6747a8..d812bed89 100644
--- a/src/windows/installer.nsi
+++ b/src/windows/installer.nsi
@@ -107,7 +107,7 @@ SectionEnd
 
 ;--------------------------------
 
-Function .onInit	
+Function .onInit    
     ;Search if qBittorrent is already installed.
     FindFirst $0 $1 "$INSTDIR\uninst.exe"
     FindClose $0
@@ -128,3 +128,17 @@ Function .onInit
     !insertmacro MUI_LANGDLL_DISPLAY
 	
 FunctionEnd
+
+Function check_instance
+
+    check:
+    FindProcDLL::FindProc "qbittorrent.exe"
+    StrCmp $R0 "1" 0 notfound
+    MessageBox MB_RETRYCANCEL|MB_ICONEXCLAMATION $(inst_warning) IDRETRY check IDCANCEL done
+
+    done:
+    Abort
+    
+    notfound:
+    
+FunctionEnd
diff --git a/src/windows/options.nsi b/src/windows/options.nsi
index 2a47b4f7a..6a5c3dea5 100644
--- a/src/windows/options.nsi
+++ b/src/windows/options.nsi
@@ -65,6 +65,7 @@ RequestExecutionLevel admin
 ;Installer Pages
 !insertmacro MUI_PAGE_WELCOME
 !insertmacro MUI_PAGE_LICENSE "license.txt"
+!define MUI_PAGE_CUSTOMFUNCTION_LEAVE check_instance
 !insertmacro MUI_PAGE_COMPONENTS
 !insertmacro MUI_PAGE_DIRECTORY
 !insertmacro MUI_PAGE_INSTFILES
@@ -73,6 +74,7 @@ RequestExecutionLevel admin
 ;--------------------------------
 ;Uninstaller Pages
 !insertmacro MUI_UNPAGE_CONFIRM
+!define MUI_PAGE_CUSTOMFUNCTION_LEAVE un.check_instance
 !insertmacro MUI_UNPAGE_COMPONENTS
 !insertmacro MUI_UNPAGE_INSTFILES
 
diff --git a/src/windows/uninstaller.nsi b/src/windows/uninstaller.nsi
index 8f3036929..89e406e3b 100644
--- a/src/windows/uninstaller.nsi
+++ b/src/windows/uninstaller.nsi
@@ -90,3 +90,17 @@ Function un.onInit
   !insertmacro MUI_UNGETLANGUAGE
   
 FunctionEnd
+
+Function un.check_instance
+
+    check:
+    FindProcDLL::FindProc "qbittorrent.exe"
+    StrCmp $R0 "1" 0 notfound
+    MessageBox MB_RETRYCANCEL|MB_ICONEXCLAMATION $(uninst_warning) IDRETRY check IDCANCEL done
+
+    done:
+    Abort
+    
+    notfound:
+    
+FunctionEnd