diff --git a/src/base/cmd/cmdHist.c b/src/base/cmd/cmdHist.c
index b0981630c..b66f48c88 100644
--- a/src/base/cmd/cmdHist.c
+++ b/src/base/cmd/cmdHist.c
@@ -50,7 +50,7 @@ ABC_NAMESPACE_IMPL_START
 void Cmd_HistoryAddCommand(    Abc_Frame_t * p, const char * command )
 {
     int nLastLooked =    10;  // do not add history if the same entry appears among the last entries
-    int nLastSaved  = 10000;  // when saving a file, save no more than this number of last entries
+    int nLastSaved  = 20000;  // when saving a file, save no more than this number of last entries
     char Buffer[ABC_MAX_STR];
     int Len;
     if ( p->fBatchMode )
@@ -117,6 +117,7 @@ void Cmd_HistoryRead( Abc_Frame_t * p )
         Vec_PtrPush( p->aHistory, Extra_UtilStrsav(Buffer) );
     }
     fclose( pFile );
+    p->iStartHistory = Vec_PtrSize(p->aHistory);
 #endif
 }
 
@@ -137,16 +138,32 @@ void Cmd_HistoryWrite( Abc_Frame_t * p, int Limit )
     FILE * pFile;
     char * pStr; 
     int i;
-    pFile = fopen( "abc.history", "wb" );
-    if ( pFile == NULL )
+    if ( 1 )
     {
-        Abc_Print( 0, "Cannot open file \"abc.history\" for writing.\n" );
-        return;
+        pFile = fopen( "abc.history", "ab" );
+        if ( pFile == NULL )
+        {
+            Abc_Print( 0, "Cannot open file \"abc.history\" for writing.\n" );
+            return;
+        }
+        Vec_PtrForEachEntryStart( char *, p->aHistory, pStr, i, p->iStartHistory )
+            fprintf( pFile, "%s\n", pStr );
+        fclose( pFile );
+        p->iStartHistory = Vec_PtrSize(p->aHistory);
+    }
+    if ( Vec_PtrSize(p->aHistory) > Limit + 1000 )
+    {
+        pFile = fopen( "abc.history", "wb" );
+        if ( pFile == NULL )
+        {
+            Abc_Print( 0, "Cannot open file \"abc.history\" for writing.\n" );
+            return;
+        }
+        Limit = Abc_MaxInt( 0, Vec_PtrSize(p->aHistory)-Limit );
+        Vec_PtrForEachEntryStart( char *, p->aHistory, pStr, i, Limit )
+            fprintf( pFile, "%s\n", pStr );
+        fclose( pFile );
     }
-    Limit = Abc_MaxInt( 0, Vec_PtrSize(p->aHistory)-Limit );
-    Vec_PtrForEachEntryStart( char *, p->aHistory, pStr, i, Limit )
-        fprintf( pFile, "%s\n", pStr );
-    fclose( pFile );
 #endif
 }
 
diff --git a/src/base/main/mainInt.h b/src/base/main/mainInt.h
index db98fbb3e..73b3ad2dd 100644
--- a/src/base/main/mainInt.h
+++ b/src/base/main/mainInt.h
@@ -67,6 +67,7 @@ struct Abc_Frame_t_
     st__table *      tAliases;      // the alias table
     st__table *      tFlags;        // the flag table
     Vec_Ptr_t *     aHistory;      // the command history
+    int             iStartHistory; // beginning of the new history file
     // the functionality
     Abc_Ntk_t *     pNtkCur;       // the current network
     Abc_Ntk_t *     pNtkBestDelay; // the current network