diff --git a/op-supernode/flags/flags.go b/op-supernode/flags/flags.go
index bf3e6580d5f..b0b9631b096 100644
--- a/op-supernode/flags/flags.go
+++ b/op-supernode/flags/flags.go
@@ -96,12 +96,12 @@ func FullDynamicFlags(chains []uint64) []cli.Flag {
 	for _, f := range opnodeflags.Flags {
 		baseName := f.Names()[0]
 		// vn.all.* env var/alias prefixing
-		allEnvs := prefixEnvVar(f, "VN_ALL_")
+		allEnvs := upgradeEnvVarPrefixes(f, opnodeflags.EnvVarPrefix, "VN_ALL")
 		allAliases := prefixAliases(f, VNFlagGlobalPrefix)
 		final = append(final, renameFlagWithEnv(f, VNFlagGlobalPrefix+baseName, allEnvs, allAliases))
 		// per-chain
 		for _, id := range chains {
-			perChainEnvs := prefixEnvVar(f, fmt.Sprintf("VN_%d_", id))
+			perChainEnvs := upgradeEnvVarPrefixes(f, opnodeflags.EnvVarPrefix, fmt.Sprintf("VN_%d", id))
 			perAliases := prefixAliases(f, fmt.Sprintf("%s%d.", VNFlagNamePrefix, id))
 			final = append(final, renameFlagWithEnv(f, fmt.Sprintf("%s%d.%s", VNFlagNamePrefix, id, baseName), perChainEnvs, perAliases))
 		}
diff --git a/op-supernode/flags/virtual_flags.go b/op-supernode/flags/virtual_flags.go
index 4c5ff50caf1..5a152ad9bf5 100644
--- a/op-supernode/flags/virtual_flags.go
+++ b/op-supernode/flags/virtual_flags.go
@@ -137,21 +137,23 @@ func renameFlagWithEnv(f cli.Flag, name string, envs []string, aliases []string)
 	}
 }
 
-// prefixEnvVar prefixes the env vars of the given flag with the given middle string
-// e.g. "VN_ALL_" or "VN_123_".
-func prefixEnvVar(f cli.Flag, mid string) []string {
+// upgradeEnvVarPrefixes returns a slice of the env vars of the given flag
+// each with a modified prefix, formed by the OP_SUPERNODE prefix
+// followed by given infix such as "VN_ALL"
+// e.g. "OP_NODE_FINALITY_DELAY" becomes "OP_SUPERNODE_VN_ALL_FINALITY_DELAY"
+// or "OP_SUPERNODE_VN_123_FINALITY_DELAY".
+func upgradeEnvVarPrefixes(f cli.Flag, existingPrefix, newInfix string) []string {
 	envs := f.(interface{ GetEnvVars() []string }).GetEnvVars()
 	if len(envs) == 0 {
 		return nil
 	}
 	out := make([]string, 0, len(envs))
 	for _, e := range envs {
-		idx := strings.Index(e, "_")
-		if idx < 0 {
-			continue
+		suffix := strings.TrimPrefix(e, existingPrefix+"_")
+		if suffix == e {
+			panic("encountered unprefixed flag")
 		}
-		suffix := e[idx+1:]
-		out = append(out, EnvVarPrefix+"_"+mid+suffix)
+		out = append(out, EnvVarPrefix+"_"+newInfix+"_"+suffix)
 	}
 	return out
 }
diff --git a/op-supernode/flags/virtual_test.go b/op-supernode/flags/virtual_test.go
index fb7058ae751..a033e78bcbe 100644
--- a/op-supernode/flags/virtual_test.go
+++ b/op-supernode/flags/virtual_test.go
@@ -6,6 +6,7 @@ import (
 	"reflect"
 	"testing"
 
+	"github.com/stretchr/testify/require"
 	"github.com/urfave/cli/v2"
 
 	opnodeflags "github.com/ethereum-optimism/optimism/op-node/flags"
@@ -84,6 +85,19 @@ func TestParseChainsVariants(t *testing.T) {
 	}
 }
 
+func TestUpgradeEnvVarPrefixes(t *testing.T) {
+	flag := &cli.StringFlag{Name: "flag", EnvVars: []string{"OP_NODE_FINALITY_DELAY"}}
+	got := upgradeEnvVarPrefixes(flag, "OP_NODE", "VN_987")
+	expected := []string{"OP_SUPERNODE_VN_987_FINALITY_DELAY"}
+	require.Equal(t, expected, got)
+	got = upgradeEnvVarPrefixes(flag, "OP_NODE", "VN_ALL")
+	expected = []string{"OP_SUPERNODE_VN_ALL_FINALITY_DELAY"}
+	require.Equal(t, expected, got)
+
+	badFlag := &cli.StringFlag{Name: "flag", EnvVars: []string{"BAD_FLAG_FINALITY_DELAY"}}
+	require.Panics(t, func() { upgradeEnvVarPrefixes(badFlag, "OP_NODE", "VN_987") })
+}
+
 func TestFullDynamicFlags_ClonesAllFlagsForChainsAndGlobal(t *testing.T) {
 	chains := []uint64{100, 200}
 	flagsOut := FullDynamicFlags(chains)