diff --git a/lm/builder/interpolate.cc b/lm/builder/interpolate.cc
index db8537448..fcd5073d8 100644
--- a/lm/builder/interpolate.cc
+++ b/lm/builder/interpolate.cc
@@ -25,6 +25,11 @@ class Callback {
 
     ~Callback() {
       for (std::size_t i = 0; i < backoffs_.size(); ++i) {
+        
+        if(prune_thresholds_[i + 1] > 0)
+          while(backoffs_[i])
+            ++backoffs_[i];
+
         if (backoffs_[i]) {
           std::cerr << "Backoffs do not match for order " << (i + 1) << std::endl;
           abort();
@@ -50,10 +55,8 @@ class Callback {
           uint64_t current_hash = util::MurmurHashNative(gram.begin(), gram.Order() * sizeof(WordIndex));
           
           const HashGamma *hashed_backoff = static_cast<const HashGamma*>(backoffs_[order_minus_1].Get());
-          while(backoffs_[order_minus_1] && current_hash != hashed_backoff->hash_value) {
+          while(current_hash != hashed_backoff->hash_value && ++backoffs_[order_minus_1]) 
             hashed_backoff = static_cast<const HashGamma*>(backoffs_[order_minus_1].Get());
-            ++backoffs_[order_minus_1];
-          }
           
           if(current_hash == hashed_backoff->hash_value) {
             pay.complete.backoff = log10(hashed_backoff->gamma);