diff --git a/src/filesystem.cpp b/src/filesystem.cpp
index 69b51dd..29acbc0 100644
--- a/src/filesystem.cpp
+++ b/src/filesystem.cpp
@@ -512,7 +512,7 @@ findFontsFolderCB(void *data, const char *, const char *fname)
 	while (s && i < sizeof(buffer))
 		buffer[i++] = tolower(*s++);
 
-	buffer[i] = '\0';
+	if(i < sizeof(buffer)) buffer[i] = '\0';
 
 	if (strcmp(buffer, "fonts") == 0)
 		PHYSFS_enumerate(fname, fontSetEnumCB, data);