diff --git a/src/slic3r/GUI/InstanceCheck.cpp b/src/slic3r/GUI/InstanceCheck.cpp
index aaf3ba3c6..d4dfa1f35 100644
--- a/src/slic3r/GUI/InstanceCheck.cpp
+++ b/src/slic3r/GUI/InstanceCheck.cpp
@@ -79,7 +79,7 @@ namespace instance_check_internal
 			return true;
 		std::wstring classNameString(className);
 		std::wstring wndTextString(wndText);
-		if (wndTextString.find(L"PrusaSlicer") == 0 && classNameString == L"wxWindowNR") {
+		if (wndTextString.find(L"PrusaSlicer") != std::wstring::npos && classNameString == L"wxWindowNR") {
 			//check if other instances has same instance hash
 			//if not it is not same version(binary) as this version 
 			HANDLE                handle = GetProp(hwnd, L"Instance_Hash_Minor");