diff --git a/dlls/ole32/stg_bigblockfile.c b/dlls/ole32/stg_bigblockfile.c
index 4aa302649fb..77abbf6286b 100644
--- a/dlls/ole32/stg_bigblockfile.c
+++ b/dlls/ole32/stg_bigblockfile.c
@@ -93,7 +93,6 @@ struct BigBlockFile
 {
     BOOL fileBased;
     ULARGE_INTEGER filesize;
-    ULONG blocksize;
     HANDLE hfile;
     HANDLE hfilemap;
     DWORD flProtect;
@@ -658,7 +657,7 @@ static HRESULT ImplBIGBLOCKFILE_WriteAt(
  * and the blocks in use list.
  */
 BigBlockFile *BIGBLOCKFILE_Construct(HANDLE hFile, ILockBytes* pLkByt, DWORD openFlags,
-                                     ULONG blocksize, BOOL fileBased)
+                                     BOOL fileBased)
 {
     BigBlockFile *This;
 
@@ -669,7 +668,6 @@ BigBlockFile *BIGBLOCKFILE_Construct(HANDLE hFile, ILockBytes* pLkByt, DWORD ope
 
     This->fileBased = fileBased;
     This->flProtect = BIGBLOCKFILE_GetProtectMode(openFlags);
-    This->blocksize = blocksize;
 
     This->maplist = NULL;
     This->victimhead = NULL;
@@ -812,31 +810,19 @@ static HRESULT BIGBLOCKFILE_GetSize(BigBlockFile *This, ULARGE_INTEGER *size)
 }
 
 /******************************************************************************
- *      BIGBLOCKFILE_EnsureExists
+ *      BIGBLOCKFILE_Expand
  *
- * Grows the file if necessary to make sure the block is valid.
+ * Grows the file to the specified size if necessary.
  */
-HRESULT BIGBLOCKFILE_EnsureExists(BigBlockFile *This, ULONG index)
+HRESULT BIGBLOCKFILE_Expand(BigBlockFile *This, ULARGE_INTEGER newSize)
 {
     ULARGE_INTEGER size;
     HRESULT hr;
 
-    /* Block index starts at -1 translate to zero based index */
-    if (index == 0xffffffff)
-        index = 0;
-    else
-        index++;
-
     hr = BIGBLOCKFILE_GetSize(This, &size);
     if(FAILED(hr)) return hr;
 
-    /* make sure that the block physically exists */
-    if ((This->blocksize * (index + 1)) > size.QuadPart)
-    {
-        ULARGE_INTEGER newSize;
-
-        newSize.QuadPart = This->blocksize * (index + 1);
+    if (newSize.QuadPart > size.QuadPart)
         hr = BIGBLOCKFILE_SetSize(This, newSize);
-    }
     return hr;
 }
diff --git a/dlls/ole32/storage32.c b/dlls/ole32/storage32.c
index fefacb11e6e..6ee60a18ce8 100644
--- a/dlls/ole32/storage32.c
+++ b/dlls/ole32/storage32.c
@@ -2639,7 +2639,6 @@ static HRESULT StorageImpl_Construct(
   This->bigBlockFile   = BIGBLOCKFILE_Construct(hFile,
                                                 pLkbyt,
                                                 openFlags,
-                                                This->bigBlockSize,
                                                 fileBased);
 
   if (This->bigBlockFile == 0)
@@ -2855,6 +2854,7 @@ static ULONG StorageImpl_GetNextFreeBigBlock(
   ULONG nextBlockIndex    = BLOCK_SPECIAL;
   int   depotIndex        = 0;
   ULONG freeBlock         = BLOCK_UNUSED;
+  ULARGE_INTEGER neededSize;
 
   depotIndex = This->prevFreeBlock / blocksPerDepot;
   depotBlockOffset = (This->prevFreeBlock % blocksPerDepot) * sizeof(ULONG);
@@ -2968,7 +2968,8 @@ static ULONG StorageImpl_GetNextFreeBigBlock(
   /*
    * make sure that the block physically exists before using it
    */
-  BIGBLOCKFILE_EnsureExists(This->bigBlockFile, freeBlock);
+  neededSize.QuadPart = StorageImpl_GetBigBlockOffset(This, freeBlock)+This->bigBlockSize;
+  BIGBLOCKFILE_Expand(This->bigBlockFile, neededSize);
 
   This->prevFreeBlock = freeBlock;
 
diff --git a/dlls/ole32/storage32.h b/dlls/ole32/storage32.h
index 9e57e30b9e2..fad5d7766f7 100644
--- a/dlls/ole32/storage32.h
+++ b/dlls/ole32/storage32.h
@@ -161,10 +161,9 @@ typedef struct BigBlockFile BigBlockFile,*LPBIGBLOCKFILE;
 BigBlockFile*  BIGBLOCKFILE_Construct(HANDLE hFile,
                                       ILockBytes* pLkByt,
                                       DWORD openFlags,
-                                      ULONG blocksize,
                                       BOOL fileBased);
 void           BIGBLOCKFILE_Destructor(LPBIGBLOCKFILE This);
-HRESULT        BIGBLOCKFILE_EnsureExists(LPBIGBLOCKFILE This, ULONG index);
+HRESULT        BIGBLOCKFILE_Expand(LPBIGBLOCKFILE This, ULARGE_INTEGER newSize);
 HRESULT        BIGBLOCKFILE_SetSize(LPBIGBLOCKFILE This, ULARGE_INTEGER newSize);
 HRESULT        BIGBLOCKFILE_ReadAt(LPBIGBLOCKFILE This, ULARGE_INTEGER offset,
            void* buffer, ULONG size, ULONG* bytesRead);