1 files changed, 5 insertions, 0 deletions
diff --git a/src/sat/asat/added.c b/src/sat/asat/added.c
index 99f1fafe..497087fb 100644
--- a/src/sat/asat/added.c
+++ b/src/sat/asat/added.c
@@ -71,6 +71,11 @@ void Asat_SolverWriteDimacs( solver * p, char * pFileName, lit* assumptionsBegin
 
     // start the file
     pFile = fopen( pFileName, "wb" );
+    if ( pFile == NULL )
+    {
+        printf( "Asat_SolverWriteDimacs(): Cannot open the ouput file.\n" );
+        return;
+    }
     fprintf( pFile, "c CNF generated by ABC on %s\n", Extra_TimeStamp() );
     fprintf( pFile, "p cnf %d %d\n", p->size, nClauses );