diff --git a/src/main.cpp b/src/main.cpp
index fe35fbaf2..a94fdc309 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1572,7 +1572,7 @@ bool CBlock::DisconnectBlock(CBlockIndex *pindex, CCoinsViewCache &view, bool *p
     }
 }
 
-void static FlushBlockFile()
+void static FlushBlockFile(bool fFinalize = false)
 {
     LOCK(cs_LastBlockFile);
 
@@ -1580,12 +1580,16 @@ void static FlushBlockFile()
 
     FILE *fileOld = OpenBlockFile(posOld);
     if (fileOld) {
+        if (fFinalize)
+            TruncateFile(fileOld, infoLastBlockFile.nSize);
         FileCommit(fileOld);
         fclose(fileOld);
     }
 
     fileOld = OpenUndoFile(posOld);
     if (fileOld) {
+        if (fFinalize)
+            TruncateFile(fileOld, infoLastBlockFile.nUndoSize);
         FileCommit(fileOld);
         fclose(fileOld);
     }
@@ -1991,7 +1995,7 @@ bool FindBlockPos(CDiskBlockPos &pos, unsigned int nAddSize, unsigned int nHeigh
     } else {
         while (infoLastBlockFile.nSize + nAddSize >= MAX_BLOCKFILE_SIZE) {
             printf("Leaving block file %i: %s\n", nLastBlockFile, infoLastBlockFile.ToString().c_str());
-            FlushBlockFile();
+            FlushBlockFile(true);
             nLastBlockFile++;
             infoLastBlockFile.SetNull();
             pblocktree->ReadBlockFileInfo(nLastBlockFile, infoLastBlockFile); // check whether data for the new file somehow already exist; can fail just fine
diff --git a/src/util.cpp b/src/util.cpp
index 6ea5e1d83..4ac66d466 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -1161,6 +1161,14 @@ int GetFilesize(FILE* file)
     return nFilesize;
 }
 
+bool TruncateFile(FILE *file, unsigned int length) {
+#if defined(WIN32)
+    return _chsize(_fileno(file), length) == 0;
+#else
+    return ftruncate(fileno(file), length) == 0;
+#endif
+}
+
 // this function tries to make a particular range of a file allocated (corresponding to disk space)
 // it is advisory, and the range specified in the arguments will never contain live data
 void AllocateFileRange(FILE *file, unsigned int offset, unsigned int length) {
diff --git a/src/util.h b/src/util.h
index 97911d749..1d2986707 100644
--- a/src/util.h
+++ b/src/util.h
@@ -193,6 +193,7 @@ bool WildcardMatch(const char* psz, const char* mask);
 bool WildcardMatch(const std::string& str, const std::string& mask);
 void FileCommit(FILE *fileout);
 int GetFilesize(FILE* file);
+bool TruncateFile(FILE *file, unsigned int length);
 void AllocateFileRange(FILE *file, unsigned int offset, unsigned int length);
 bool RenameOver(boost::filesystem::path src, boost::filesystem::path dest);
 boost::filesystem::path GetDefaultDataDir();