diff --git a/source/install/nsp.cpp b/source/install/nsp.cpp
index 86703b5..ecafa2b 100644
--- a/source/install/nsp.cpp
+++ b/source/install/nsp.cpp
@@ -83,14 +83,18 @@ namespace tin::install::nsp
 		{
 			const PFS0FileEntry* fileEntry = this->GetFileEntry(i);
 			std::string name(this->GetFileEntryName(fileEntry));
-
+			auto foundExtension = name.substr(name.find(".") + 1);
+				
 			// fix cert filname extension becoming corrupted when xcz/nsz is installing certs/ticks.
-			int pos = 0;
-			std::string mystr = name;
-			pos = mystr.find_last_of('.');
-			mystr = mystr.substr(5, pos);
-			//auto foundExtension = name.substr(name.find(".") + 1);
-			auto foundExtension = mystr.substr(mystr.find(".") + 1);
+			std::string cert ("cert");
+			std::size_t found = name.find(cert);
+			if (found!=std::string::npos){
+				int pos = 0;
+				std::string mystr = name;
+				pos = mystr.find_last_of('.');
+				mystr = mystr.substr(5, pos);
+				foundExtension = mystr.substr(mystr.find(".") + 1);
+			}
 
 			if (foundExtension == extension)
 				entryList.push_back(fileEntry);
diff --git a/source/install/xci.cpp b/source/install/xci.cpp
index ef54b4a..254bb02 100644
--- a/source/install/xci.cpp
+++ b/source/install/xci.cpp
@@ -158,15 +158,19 @@ namespace tin::install::xci
 		{
 			const HFS0FileEntry* fileEntry = this->GetFileEntry(i);
 			std::string name(this->GetFileEntryName(fileEntry));
-
+			auto foundExtension = name.substr(name.find(".") + 1);
+			
 			// fix cert filname extension becoming corrupted when xcz/nsz is installing certs/ticks.
-			int pos = 0;
-			std::string mystr = name;
-			pos = mystr.find_last_of('.');
-			mystr = mystr.substr(5, pos);
-			//auto foundExtension = name.substr(name.find(".") + 1);
-			auto foundExtension = mystr.substr(mystr.find(".") + 1);
-
+			std::string cert ("cert");
+			std::size_t found = name.find(cert);
+			if (found!=std::string::npos){
+				int pos = 0;
+				std::string mystr = name;
+				pos = mystr.find_last_of('.');
+				mystr = mystr.substr(5, pos);
+				foundExtension = mystr.substr(mystr.find(".") + 1);
+			}
+			
 			if (foundExtension == extension)
 				entryList.push_back(fileEntry);
 		}