diff --git a/.gitmodules b/.gitmodules
index ef341c24f..5c7cb0376 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -143,7 +143,7 @@
 	path = vendor/zerokit
 	url = https://github.com/vacp2p/zerokit.git
 	ignore = dirty
-	branch = v0.3.2
+	branch = v0.3.4
 [submodule "vendor/nim-regex"]
 	path = vendor/nim-regex
 	url = https://github.com/nitely/nim-regex.git
diff --git a/Makefile b/Makefile
index e083d3032..586bdb82e 100644
--- a/Makefile
+++ b/Makefile
@@ -119,16 +119,17 @@ clean: | clean-libbacktrace
 .PHONY: librln
 
 LIBRLN_BUILDDIR := $(CURDIR)/vendor/zerokit
+LIBRLN_VERSION := v0.3.4
 
 ifeq ($(OS),Windows_NT)
 LIBRLN_FILE := rln.lib
 else
-LIBRLN_FILE := librln.a
+LIBRLN_FILE := librln_$(LIBRLN_VERSION).a
 endif
 
 $(LIBRLN_FILE):
 	echo -e $(BUILD_MSG) "$@" && \
-		./scripts/build_rln.sh $(LIBRLN_BUILDDIR)
+		./scripts/build_rln.sh $(LIBRLN_BUILDDIR) $(LIBRLN_VERSION) $(LIBRLN_FILE)
 
 
 librln: | $(LIBRLN_FILE)
diff --git a/scripts/build_rln.sh b/scripts/build_rln.sh
index 3fda88ab8..dec443dc4 100755
--- a/scripts/build_rln.sh
+++ b/scripts/build_rln.sh
@@ -7,25 +7,45 @@ set -e
 
 # first argument is the build directory
 build_dir=$1
+rln_version=$2
+output_filename=$3
 
 if [[ -z "$build_dir" ]]; then
     echo "No build directory specified"
     exit 1
 fi
 
+if [[ -z "$rln_version" ]]; then
+    echo "No rln version specified"
+    exit 1
+fi
+
+if [[ -z "$output_filename" ]]; then
+    echo "No output filename specified"
+    exit 1
+fi
+
 # Get the host triplet
 host_triplet=$(rustup show | grep "Default host: " | cut -d' ' -f3)
 
 # Download the prebuilt rln library if it is available
-if curl --silent --fail-with-body -L "https://github.com/vacp2p/zerokit/releases/download/v0.3.2/$host_triplet-rln.tar.gz" >> "$host_triplet-rln.tar.gz"
+if curl --silent --fail-with-body -L "https://github.com/vacp2p/zerokit/releases/download/$rln_version/$host_triplet-rln.tar.gz" >> "$host_triplet-rln.tar.gz"
 then
     echo "Downloaded $host_triplet-rln.tar.gz"
     tar -xzf "$host_triplet-rln.tar.gz"
-    mv release/librln.a .
+    mv release/librln.a $output_filename
     rm -rf "$host_triplet-rln.tar.gz" release
 else
     echo "Failed to download $host_triplet-rln.tar.gz"
     # Build rln instead
+    # first, check if submodule version = version in Makefile
+    submodule_version=$(cargo metadata --format-version=1 --no-deps | jq '.packages[] | select(.name == "rln") | .version')
+    if [[ "v$submodule_version" != "$rln_version" ]]; then
+        echo "Submodule version (v$submodule_version) does not match version in Makefile ($rln_version)"
+        echo "Please update the submodule to $rln_version"
+        exit 1
+    fi
+    # if submodule version = version in Makefile, build rln
     cargo build --release -p rln --manifest-path "$build_dir/rln/Cargo.toml"
-    cp "$build_dir/target/release/librln.a" .
+    cp "$build_dir/target/release/librln.a" $output_filename
 fi
diff --git a/tests/waku_rln_relay/test_waku_rln_relay.nim b/tests/waku_rln_relay/test_waku_rln_relay.nim
index d99bc1812..bb032f964 100644
--- a/tests/waku_rln_relay/test_waku_rln_relay.nim
+++ b/tests/waku_rln_relay/test_waku_rln_relay.nim
@@ -210,6 +210,7 @@ suite "Waku rln relay":
       idCredentialRes.isOk()
     check:
       rln.insertMembers(0, @[idCredentialRes.get().idCommitment])
+      rln.leavesSet() == 1
 
   test "insertMember rln utils":
     # create an RLN instance which also includes an empty Merkle tree
diff --git a/vendor/zerokit b/vendor/zerokit
index b51896c3a..b903d8d74 160000
--- a/vendor/zerokit
+++ b/vendor/zerokit
@@ -1 +1 @@
-Subproject commit b51896c3a710f567fc7e054681767d6547a8eb9b
+Subproject commit b903d8d740e0b8b82057bcc5377ddce05ae5676b
diff --git a/waku/waku_rln_relay/group_manager/on_chain/group_manager.nim b/waku/waku_rln_relay/group_manager/on_chain/group_manager.nim
index f23cc0d30..618a64d00 100644
--- a/waku/waku_rln_relay/group_manager/on_chain/group_manager.nim
+++ b/waku/waku_rln_relay/group_manager/on_chain/group_manager.nim
@@ -106,7 +106,7 @@ method atomicBatch*(g: OnchainGroupManager,
   if not operationSuccess:
     raise newException(ValueError, "atomic batch operation failed")
   # TODO: when slashing is enabled, we need to track slashed members
-  waku_rln_number_registered_memberships.set(int64(start.int + idCommitments.len - toRemoveIndices.len))
+  waku_rln_number_registered_memberships.set(int64(g.rlnInstance.leavesSet()))
 
   if g.registerCb.isSome():
     var membersSeq = newSeq[Membership]()
@@ -352,8 +352,10 @@ proc startOnchainSync(g: OnchainGroupManager): Future[void] {.async.} =
   let blockChunkSize = 2_000
 
   var fromBlock = if g.latestProcessedBlock > g.rlnContractDeployedBlockNumber:
+    info "syncing from last processed block", blockNumber = g.latestProcessedBlock
     g.latestProcessedBlock + 1
   else:
+    info "syncing from rln contract deployed block", blockNumber = g.rlnContractDeployedBlockNumber
     g.rlnContractDeployedBlockNumber
 
   try:
@@ -482,6 +484,7 @@ method init*(g: OnchainGroupManager): Future[void] {.async.} =
   var deployedBlockNumber: Uint256
   try:
     deployedBlockNumber = await rlnContract.deployedBlockNumber().call()
+    debug "using rln storage", deployedBlockNumber, rlnContractAddress
   except CatchableError:
     raise newException(ValueError,
                        "could not get the deployed block number: " & getCurrentExceptionMsg())
@@ -504,6 +507,7 @@ method init*(g: OnchainGroupManager): Future[void] {.async.} =
     except CatchableError:
       error "failed to restart group sync", error = getCurrentExceptionMsg()
 
+  waku_rln_number_registered_memberships.set(int64(g.rlnInstance.leavesSet()))
   g.initialized = true
 
 method stop*(g: OnchainGroupManager): Future[void] {.async.} =
diff --git a/waku/waku_rln_relay/rln/rln_interface.nim b/waku/waku_rln_relay/rln/rln_interface.nim
index 828b20548..c3668c6c6 100644
--- a/waku/waku_rln_relay/rln/rln_interface.nim
+++ b/waku/waku_rln_relay/rln/rln_interface.nim
@@ -59,6 +59,10 @@ proc get_leaf*(ctx: ptr RLN, index: uint, output_buffer: ptr Buffer): bool {.imp
 ## the output_buffer holds a serialized leaf of 32 bytes
 ## the return bool value indicates the success or failure of the operation
 
+proc leaves_set*(ctx: ptr RLN): uint {.importc: "leaves_set".}
+## gets the number of leaves set in the tree stored by ctx
+## the return uint value indicates the number of leaves set in the tree
+
 proc init_tree_with_leaves*(ctx: ptr RLN, input_buffer: ptr Buffer): bool {.importc: "init_tree_with_leaves".}
 ## sets multiple leaves in the tree stored by ctx to the value passed by input_buffer
 ## the input_buffer holds a serialized vector of leaves (32 bytes each)