diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 7408a77c..fbe768bb 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -358,8 +358,8 @@ namespace {
                 score += RookOnPawn * popcount(pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s]);
 
             // Bonus for rook on an open or semi-open file
-            if (pe->semiopen_file(Us, file_of(s)))
-                score += RookOnFile[bool(pe->semiopen_file(Them, file_of(s)))];
+            if (pos.semiopen_file(Us, file_of(s)))
+                score += RookOnFile[bool(pos.semiopen_file(Them, file_of(s)))];
 
             // Penalty when trapped by the king, even more if the king cannot castle
             else if (mob <= 3)
@@ -720,7 +720,7 @@ namespace {
 
     int bonus = popcount(safe) + popcount(behind & safe);
     int weight =  pos.count<ALL_PIECES>(Us)
-                - 2 * popcount(pe->semiopenFiles[WHITE] & pe->semiopenFiles[BLACK]);
+               - (16 - pos.count<PAWN>()) / 4;
 
     Score score = make_score(bonus * weight * weight / 16, 0);
 
diff --git a/src/pawns.cpp b/src/pawns.cpp
index b034f478..7e29f506 100644
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -77,7 +77,6 @@ namespace {
     Bitboard theirPawns = pos.pieces(Them, PAWN);
 
     e->passedPawns[Us] = e->pawnAttacksSpan[Us] = e->weakUnopposed[Us] = 0;
-    e->semiopenFiles[Us] = 0xFF;
     e->kingSquares[Us]   = SQ_NONE;
     e->pawnAttacks[Us]   = pawn_attacks_bb<Us>(ourPawns);
     e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares);
@@ -91,7 +90,6 @@ namespace {
         File f = file_of(s);
         Rank r = relative_rank(Us, s);
 
-        e->semiopenFiles[Us]   &= ~(1 << f);
         e->pawnAttacksSpan[Us] |= pawn_attack_span(Us, s);
 
         // Flag the pawn
diff --git a/src/pawns.h b/src/pawns.h
index 71d18ee8..5f5411f6 100644
--- a/src/pawns.h
+++ b/src/pawns.h
@@ -40,10 +40,6 @@ struct Entry {
   int weak_unopposed(Color c) const { return weakUnopposed[c]; }
   int passed_count() const { return passedCount; }
 
-  int semiopen_file(Color c, File f) const {
-    return semiopenFiles[c] & (1 << f);
-  }
-
   int pawns_on_same_color_squares(Color c, Square s) const {
     return pawnsOnSquares[c][bool(DarkSquares & s)];
   }
@@ -69,7 +65,6 @@ struct Entry {
   Score kingSafety[COLOR_NB];
   int weakUnopposed[COLOR_NB];
   int castlingRights[COLOR_NB];
-  int semiopenFiles[COLOR_NB];
   int pawnsOnSquares[COLOR_NB][COLOR_NB]; // [color][light/dark squares]
   int passedCount;
 };
diff --git a/src/position.h b/src/position.h
index 03c00148..1351d0d1 100644
--- a/src/position.h
+++ b/src/position.h
@@ -95,6 +95,7 @@ public:
   template<PieceType Pt> int count() const;
   template<PieceType Pt> const Square* squares(Color c) const;
   template<PieceType Pt> Square square(Color c) const;
+  int semiopen_file(Color c, File f) const;
 
   // Castling
   int castling_rights(Color c) const;
@@ -260,6 +261,10 @@ inline Square Position::ep_square() const {
   return st->epSquare;
 }
 
+inline int Position::semiopen_file(Color c, File f) const {
+  return !(pieces(c, PAWN) & file_bb(f));
+}
+
 inline bool Position::can_castle(CastlingRight cr) const {
   return st->castlingRights & cr;
 }