diff --git a/code/nel/tools/3d/build_interface/main.cpp b/code/nel/tools/3d/build_interface/main.cpp
index 2a5cef8f5..4ed3b46a6 100644
--- a/code/nel/tools/3d/build_interface/main.cpp
+++ b/code/nel/tools/3d/build_interface/main.cpp
@@ -477,7 +477,7 @@ int main(int argc, char **argv)
 	{
 		fmtName = fmtName.substr(0, fmtName.rfind('.'));
 		fmtName += ".txt";
-		FILE *f = nlfopen(fmtName, "wt");
+		FILE *f = nlfopen(fmtName, "wb");
 		if (f != NULL)
 		{
 			for (sint i = 0; i < mapSize; ++i)
@@ -511,7 +511,7 @@ int main(int argc, char **argv)
 		// Write subset UV text file
 		fmtName = fmtName.substr(0, fmtName.rfind('.'));
 		fmtName += ".txt";
-		FILE *f = nlfopen(fmtName, "wt");
+		FILE *f = nlfopen(fmtName, "wb");
 
 		if (f == NULL)
 		{