1 files changed, 5 insertions, 0 deletions

diff --git a/src/tools/bnfcompile.cpp b/src/tools/bnfcompile.cpp
index 011ec84..defb16b 100644
--- a/src/tools/bnfcompile.cpp
+++ b/src/tools/bnfcompile.cpp
@@ -390,6 +390,11 @@ private:
 
 int main( int argc, char *argv[] )
 {
+        if( argc < 2 )
+        {
+                println("Provide an input filename as the first parameter.");
+                return 0;
+        }
         File fIn( argv[1], File::Read );
 
         BnfLexer bl( fIn );