diff --git a/src/aig/gia/gia.h b/src/aig/gia/gia.h
index ee79ccd7a..1d0290c04 100644
--- a/src/aig/gia/gia.h
+++ b/src/aig/gia/gia.h
@@ -1358,7 +1358,7 @@ extern Gia_Man_t *         Gia_ManDupZero( Gia_Man_t * p );
 extern Gia_Man_t *         Gia_ManDupPerm( Gia_Man_t * p, Vec_Int_t * vPiPerm );
 extern Gia_Man_t *         Gia_ManDupPermFlop( Gia_Man_t * p, Vec_Int_t * vFfPerm );
 extern Gia_Man_t *         Gia_ManDupPermFlopGap( Gia_Man_t * p, Vec_Int_t * vFfPerm );
-extern void                Gia_ManDupAppend( Gia_Man_t * p, Gia_Man_t * pTwo );
+extern void                Gia_ManDupAppend( Gia_Man_t * p, Gia_Man_t * pTwo, int fShareCis );
 extern void                Gia_ManDupAppendShare( Gia_Man_t * p, Gia_Man_t * pTwo );
 extern Gia_Man_t *         Gia_ManDupAppendNew( Gia_Man_t * pOne, Gia_Man_t * pTwo );
 extern Gia_Man_t *         Gia_ManDupAppendCones( Gia_Man_t * p, Gia_Man_t ** ppCones, int nCones, int fOnlyRegs );
diff --git a/src/aig/gia/giaDup.c b/src/aig/gia/giaDup.c
index cca6f3d4c..be6eef7a2 100644
--- a/src/aig/gia/giaDup.c
+++ b/src/aig/gia/giaDup.c
@@ -1134,7 +1134,7 @@ Gia_Man_t * Gia_ManDupRandPerm( Gia_Man_t * p )
   SeeAlso     []
 
 ***********************************************************************/
-void Gia_ManDupAppend( Gia_Man_t * pNew, Gia_Man_t * pTwo )
+void Gia_ManDupAppend( Gia_Man_t * pNew, Gia_Man_t * pTwo, int fShareCis )
 {
     Gia_Obj_t * pObj;
     int i;
@@ -1148,7 +1148,7 @@ void Gia_ManDupAppend( Gia_Man_t * pNew, Gia_Man_t * pTwo )
         if ( Gia_ObjIsAnd(pObj) )
             pObj->Value = Gia_ManAppendAnd( pNew, Gia_ObjFanin0Copy(pObj), Gia_ObjFanin1Copy(pObj) );
         else if ( Gia_ObjIsCi(pObj) )
-            pObj->Value = Gia_ManAppendCi( pNew );
+            pObj->Value = fShareCis ? Gia_ManCiLit(pNew, Gia_ObjCioId(pObj)) : Gia_ManAppendCi( pNew );
         else if ( Gia_ObjIsCo(pObj) )
             pObj->Value = Gia_ManAppendCo( pNew, Gia_ObjFanin0Copy(pObj) );
     }
diff --git a/src/base/abci/abc.c b/src/base/abci/abc.c
index 146f54ac8..d6fd5c5c6 100644
--- a/src/base/abci/abc.c
+++ b/src/base/abci/abc.c
@@ -39767,13 +39767,16 @@ int Abc_CommandAbc9Append( Abc_Frame_t * pAbc, int argc, char ** argv )
     char * FileName, * pTemp;
     char ** pArgvNew;
     int nArgcNew;
-    int c;
+    int c, fShareCis = 0;
     int fVerbose = 0;
     Extra_UtilGetoptReset();
-    while ( ( c = Extra_UtilGetopt( argc, argv, "vh" ) ) != EOF )
+    while ( ( c = Extra_UtilGetopt( argc, argv, "ivh" ) ) != EOF )
     {
         switch ( c )
         {
+        case 'i':
+            fShareCis ^= 1;
+            break;
         case 'v':
             fVerbose ^= 1;
             break;
@@ -39813,14 +39816,20 @@ int Abc_CommandAbc9Append( Abc_Frame_t * pAbc, int argc, char ** argv )
         Abc_Print( -1, "Reading AIGER has failed.\n" );
         return 0;
     }
+    if ( fShareCis && Gia_ManCiNum(pAbc->pGia) != Gia_ManCiNum(pSecond) )
+    {
+        Abc_Print( -1, "The AIGs have different number of combinational inputs.\n" );
+        return 0;
+    }
     // compute the miter
-    Gia_ManDupAppend( pAbc->pGia, pSecond );
+    Gia_ManDupAppend( pAbc->pGia, pSecond, fShareCis );
     Gia_ManStop( pSecond );
     return 0;
 
 usage:
-    Abc_Print( -2, "usage: &append [-vh] <file>\n" );
+    Abc_Print( -2, "usage: &append [-ivh] <file>\n" );
     Abc_Print( -2, "\t         appends <file> to the current AIG using new PIs and POs\n" );
+    Abc_Print( -2, "\t-i     : toggle sharing combinational inputs [default = %s]\n", fShareCis? "yes": "no" );
     Abc_Print( -2, "\t-v     : toggle printing verbose information [default = %s]\n", fVerbose? "yes": "no" );
     Abc_Print( -2, "\t-h     : print the command usage\n");
     Abc_Print( -2, "\t<file> : AIGER file with the design to miter\n");