diff --git a/src/map/if/ifLibLut.c b/src/map/if/ifLibLut.c
index 26fa137ba..1033cc1f3 100644
--- a/src/map/if/ifLibLut.c
+++ b/src/map/if/ifLibLut.c
@@ -75,6 +75,7 @@ If_LibLut_t * If_LibLutRead( char * FileName )
             Abc_Print( 1, "Error in the LUT library file \"%s\".\n", FileName );
             ABC_FREE( p->pName );
             ABC_FREE( p );
+            fclose( pFile );
             return NULL;
         }
 
@@ -93,6 +94,7 @@ If_LibLut_t * If_LibLutRead( char * FileName )
             ABC_FREE( p->pName );
             ABC_FREE( p );
             Abc_Print( 1, "LUT %d has too many pins (%d). Max allowed is %d.\n", i, k, i );
+            fclose( pFile );
             return NULL;
         }
 
@@ -105,6 +107,7 @@ If_LibLut_t * If_LibLutRead( char * FileName )
             ABC_FREE( p->pName );
             ABC_FREE( p );
             Abc_Print( 1, "Skipping LUTs of size more than %d.\n", i );
+            fclose( pFile );
             return NULL;
         }
         i++;
@@ -136,6 +139,7 @@ If_LibLut_t * If_LibLutRead( char * FileName )
         }
     }
 
+    fclose( pFile );
     return p;
 }
 
diff --git a/src/opt/sbd/sbdCnf.c b/src/opt/sbd/sbdCnf.c
index 6291baedc..8705858e6 100644
--- a/src/opt/sbd/sbdCnf.c
+++ b/src/opt/sbd/sbdCnf.c
@@ -44,7 +44,7 @@ ABC_NAMESPACE_IMPL_START
 ***********************************************************************/
 void Sbd_PrintCnf( Vec_Str_t * vCnf )
 {
-    char Entry;
+    signed char Entry;
     int i, Lit;
     Vec_StrForEachEntry( vCnf, Entry, i )
     {
@@ -121,7 +121,7 @@ int Sbd_TruthToCnf( word Truth, int nVars, Vec_Int_t * vCover, Vec_Str_t * vCnf
 void Sbd_TranslateCnf( Vec_Wec_t * vRes, Vec_Str_t * vCnf, Vec_Int_t * vFaninMap, int iPivotVar )
 {
     Vec_Int_t * vClause;
-    char Entry;
+    signed char Entry;
     int i, Lit;
     Vec_WecClear( vRes );
     vClause = Vec_WecPushLevel( vRes );
diff --git a/src/opt/sfm/sfmCnf.c b/src/opt/sfm/sfmCnf.c
index 0ab92258b..b4dd11f89 100644
--- a/src/opt/sfm/sfmCnf.c
+++ b/src/opt/sfm/sfmCnf.c
@@ -45,7 +45,7 @@ ABC_NAMESPACE_IMPL_START
 ***********************************************************************/
 void Sfm_PrintCnf( Vec_Str_t * vCnf )
 {
-    char Entry;
+    signed char Entry;
     int i, Lit;
     Vec_StrForEachEntry( vCnf, Entry, i )
     {
@@ -153,7 +153,7 @@ Vec_Wec_t * Sfm_CreateCnf( Sfm_Ntk_t * p )
 void Sfm_TranslateCnf( Vec_Wec_t * vRes, Vec_Str_t * vCnf, Vec_Int_t * vFaninMap, int iPivotVar )
 {
     Vec_Int_t * vClause;
-    char Entry;
+    signed char Entry;
     int i, Lit;
     Vec_WecClear( vRes );
     vClause = Vec_WecPushLevel( vRes );