diff --git a/resource/main.cpp b/resource/main.cpp
index 4eddb8b..242f9bb 100644
--- a/resource/main.cpp
+++ b/resource/main.cpp
@@ -1,6 +1,5 @@
 #include <cstdio>
 #include <string>
-#include <regex>
 
 using namespace std;
 
@@ -58,11 +57,16 @@ int main(int argc, char *argv[])
 	string outFilename(argv[1]);
 	string packName = outFilename.substr(outFilename.find_last_of('/')+1);
 	packName = packName.substr(0, packName.find_first_of('.'));
-    if(!regex_match(packName, regex("[a-zA-Z0-9]+")))
-	{
-        printf("error : \"%s\" is an invalid resource pack name, it must match this regex : [a-zA-Z0-9]+\n", packName.c_str());
-        return EXIT_SUCCESS;
-	}
+    for(char c : packName)
+    {
+        if(c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9')
+            ; // OK
+        else
+        {
+            printf("error : \"%s\" is an invalid resource pack name, it must match this regex : [a-zA-Z0-9]+\n", packName.c_str());
+            return EXIT_SUCCESS;
+        }
+    }
     FILE *out = fopen(outFilename.c_str(), "w");
     if(out == NULL)
     {