diff --git a/dagger/stores/blockstore.nim b/dagger/stores/blockstore.nim
index 90a06173..7288a454 100644
--- a/dagger/stores/blockstore.nim
+++ b/dagger/stores/blockstore.nim
@@ -20,6 +20,7 @@ import ../blocktype
 export blocktype, libp2p
 
 type
+  OnBlock* = proc(blk: Block): Future[void] {.upraises: [], gcsafe.}
   BlockStore* = ref object of RootObj
 
 method getBlock*(
@@ -52,7 +53,7 @@ method hasBlock*(s: BlockStore, cid: Cid): bool {.base.} =
 
   return false
 
-method blockList*(s: BlockStore): Future[seq[Cid]] {.base.} =
+method listBlocks*(s: BlockStore, onBlock: OnBlock): Future[void] {.base.} =
   ## Get the list of blocks in the BlockStore. This is an intensive operation
   ##
 
diff --git a/dagger/stores/cachestore.nim b/dagger/stores/cachestore.nim
index ddcd730f..abe642df 100644
--- a/dagger/stores/cachestore.nim
+++ b/dagger/stores/cachestore.nim
@@ -68,8 +68,12 @@ method hasBlock*(self: CacheStore, cid: Cid): bool =
 
   cid in self.cache
 
-method blockList*(s: CacheStore): Future[seq[Cid]] {.async.} =
-  return toSeq(s.cache.keys)
+method listBlocks*(s: CacheStore, onBlock: OnBlock) {.async.} =
+  for cid in toSeq(s.cache.keys):
+    without blk =? (await s.getBlock(cid)):
+      trace "Couldn't get block", cid = $cid
+
+    await onBlock(blk)
 
 func putBlockSync(self: CacheStore, blk: Block): bool =
 
diff --git a/dagger/stores/fsstore.nim b/dagger/stores/fsstore.nim
index 4870e3fd..735fc65a 100644
--- a/dagger/stores/fsstore.nim
+++ b/dagger/stores/fsstore.nim
@@ -90,7 +90,7 @@ method putBlock*(
     trace "Unable to store block", path, cid = blk.cid, error
     return false
 
-  if await self.cache.putBlock(blk):
+  if not (await self.cache.putBlock(blk)):
     trace "Unable to store block in cache", cid = blk.cid
 
   return true
@@ -113,8 +113,8 @@ method delBlock*(
     trace "Unable to delete block", path, cid, error
     return false
 
-  if await self.cache.delBlock(cid):
-    trace "Unable to store block in cache", cid
+  if not (await self.cache.delBlock(cid)):
+    trace "Unable to delete block from cache", cid
 
   return true
 
@@ -129,21 +129,25 @@ method hasBlock*(self: FSStore, cid: Cid): bool =
 
   self.blockPath(cid).isFile()
 
-method blockList*(s: FSStore): Future[seq[Cid]] {.async.} =
-  ## Very expensive AND blocking!
-
-  debug "finding all blocks in store"
-  for (pkind, folderPath) in s.repoDir.walkDir():
+method listBlocks*(self: FSStore, onBlock: OnBlock) {.async.} =
+  debug "Finding all blocks in store"
+  for (pkind, folderPath) in self.repoDir.walkDir():
     if pkind != pcDir: continue
     let baseName = basename(folderPath)
-    if baseName.len != s.postfixLen: continue
+    if baseName.len != self.postfixLen: continue
 
     for (fkind, filePath) in folderPath.walkDir(false):
       if fkind != pcFile: continue
       let cid = Cid.init(basename(filePath))
       if cid.isOk:
-        result.add(cid.get())
-  return result
+        # getting a weird `Error: unhandled exception: index 1 not in 0 .. 0 [IndexError]`
+        # compilation error if using different syntax/construct bellow
+        try:
+          await onBlock((await self.getBlock(cid.tryGet())).tryGet())
+        except CatchableError as exc:
+          trace "Couldn't get block", cid = $(cid.get())
+
+      await sleepAsync(100.millis) # avoid blocking
 
 proc new*(
   T: type FSStore,
diff --git a/dagger/stores/networkstore.nim b/dagger/stores/networkstore.nim
index 0d2320e0..d9d27612 100644
--- a/dagger/stores/networkstore.nim
+++ b/dagger/stores/networkstore.nim
@@ -42,10 +42,10 @@ method getBlock*(
   trace "Getting block", cid
   without var blk =? (await self.localStore.getBlock(cid)):
     trace "Couldn't get from local store", cid
-    blk = try:
-      await self.engine.requestBlock(cid)
+    try:
+      blk = await self.engine.requestBlock(cid)
     except CatchableError as exc:
-      trace "Exception requestig block", cid, exc = exc.msg
+      trace "Exception requesting block", cid, exc = exc.msg
       return failure(exc.msg)
 
   trace "Retrieved block from local store", cid