diff --git a/crypto/block/block.cpp b/crypto/block/block.cpp
index 98546a2d4..302a2aa46 100644
--- a/crypto/block/block.cpp
+++ b/crypto/block/block.cpp
@@ -1319,6 +1319,36 @@ CurrencyCollection CurrencyCollection::operator-(td::RefInt256 other_grams) cons
   }
 }
 
+bool CurrencyCollection::clamp(const CurrencyCollection& other) {
+  if (!is_valid() || !other.is_valid()) {
+    return invalidate();
+  }
+  grams = std::min(grams, other.grams);
+  vm::Dictionary dict1{extra, 32}, dict2(other.extra, 32);
+  bool ok = dict1.check_for_each([&](td::Ref<vm::CellSlice> cs1, td::ConstBitPtr key, int n) {
+    CHECK(n == 32);
+    td::Ref<vm::CellSlice> cs2 = dict2.lookup(key, 32);
+    td::RefInt256 val1 = tlb::t_VarUIntegerPos_32.as_integer(cs1);
+    if (val1.is_null()) {
+      return false;
+    }
+    td::RefInt256 val2 = cs2.is_null() ? td::zero_refint() : tlb::t_VarUIntegerPos_32.as_integer(cs2);
+    if (val2.is_null()) {
+      return false;
+    }
+    if (val1 > val2) {
+      if (val2->sgn() == 0) {
+        dict1.lookup_delete(key, 32);
+      } else {
+        dict1.set(key, 32, cs2);
+      }
+    }
+    return true;
+  });
+  extra = dict1.get_root_cell();
+  return ok || invalidate();
+}
+
 bool CurrencyCollection::operator==(const CurrencyCollection& other) const {
   return is_valid() && other.is_valid() && !td::cmp(grams, other.grams) &&
          (extra.not_null() == other.extra.not_null()) &&
diff --git a/crypto/block/block.h b/crypto/block/block.h
index 56e6dd38a..f64f00a87 100644
--- a/crypto/block/block.h
+++ b/crypto/block/block.h
@@ -390,6 +390,7 @@ struct CurrencyCollection {
   CurrencyCollection operator-(const CurrencyCollection& other) const;
   CurrencyCollection operator-(CurrencyCollection&& other) const;
   CurrencyCollection operator-(td::RefInt256 other_grams) const;
+  bool clamp(const CurrencyCollection& other);
   bool store(vm::CellBuilder& cb) const;
   bool store_or_zero(vm::CellBuilder& cb) const;
   bool fetch(vm::CellSlice& cs);
diff --git a/crypto/block/transaction.cpp b/crypto/block/transaction.cpp
index a32bad52f..f4ad57ce8 100644
--- a/crypto/block/transaction.cpp
+++ b/crypto/block/transaction.cpp
@@ -2760,22 +2760,21 @@ int Transaction::try_action_reserve_currency(vm::CellSlice& cs, ActionPhase& ap,
     LOG(DEBUG) << "cannot reserve a negative amount: " << reserve.to_str();
     return -1;
   }
-  if (reserve.grams > ap.remaining_balance.grams) {
-    if (mode & 2) {
-      reserve.grams = ap.remaining_balance.grams;
-    } else {
-      LOG(DEBUG) << "cannot reserve " << reserve.grams << " nanograms : only " << ap.remaining_balance.grams
-                 << " available";
-      return 37;  // not enough grams
+  if (mode & 2) {
+    if (!reserve.clamp(ap.remaining_balance)) {
+      LOG(DEBUG) << "failed to clamp reserve amount" << mode;
+      return -1;
     }
   }
+  if (reserve.grams > ap.remaining_balance.grams) {
+    LOG(DEBUG) << "cannot reserve " << reserve.grams << " nanograms : only " << ap.remaining_balance.grams
+               << " available";
+    return 37;  // not enough grams
+  }
   if (!block::sub_extra_currency(ap.remaining_balance.extra, reserve.extra, newc.extra)) {
     LOG(DEBUG) << "not enough extra currency to reserve: " << block::CurrencyCollection{0, reserve.extra}.to_str()
                << " required, only " << block::CurrencyCollection{0, ap.remaining_balance.extra}.to_str()
                << " available";
-    if (mode & 2) {
-      // TODO: process (mode & 2) correctly by setting res_extra := inf (reserve.extra, ap.remaining_balance.extra)
-    }
     return 38;  // not enough (extra) funds
   }
   newc.grams = ap.remaining_balance.grams - reserve.grams;