diff --git a/CHANGELOG.md b/CHANGELOG.md
index 52894d9d00..60e06a1e86 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Fix race on startup sync. [#3162](https://github.com/evstack/ev-node/pull/3162)
+- Strict raft state. [#3167](https://github.com/evstack/ev-node/pull/3167)
 
 ## v1.0.0
 
diff --git a/pkg/raft/types.go b/pkg/raft/types.go
index bb5c6728b2..968d9aa959 100644
--- a/pkg/raft/types.go
+++ b/pkg/raft/types.go
@@ -11,10 +11,10 @@ type RaftBlockState = pb.RaftBlockState
 
 // assertValid checks basic constraints but does not ensure that no gaps exist or chain continuity
 func assertValid(s *RaftBlockState, next *RaftBlockState) error {
-	if s.Height > next.Height {
+	if s.Height >= next.Height {
 		return fmt.Errorf("invalid height: %d > %d", s.Height, next.Height)
 	}
-	if s.Timestamp > next.Timestamp {
+	if s.Timestamp >= next.Timestamp {
 		return fmt.Errorf("invalid timestamp: %d > %d", s.Timestamp, next.Timestamp)
 	}
 	return nil
diff --git a/pkg/raft/types_test.go b/pkg/raft/types_test.go
new file mode 100644
index 0000000000..bb22b5679f
--- /dev/null
+++ b/pkg/raft/types_test.go
@@ -0,0 +1,56 @@
+package raft
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestAssertValid(t *testing.T) {
+	specs := map[string]struct {
+		s      *RaftBlockState
+		next   *RaftBlockState
+		expErr bool
+	}{
+		"ok": {
+			s:    &RaftBlockState{Height: 10, Timestamp: 100},
+			next: &RaftBlockState{Height: 11, Timestamp: 101},
+		},
+		"all equal": {
+			s:      &RaftBlockState{Height: 10, Timestamp: 100},
+			next:   &RaftBlockState{Height: 10, Timestamp: 100},
+			expErr: true,
+		},
+		"equal height": {
+			s:      &RaftBlockState{Height: 10, Timestamp: 100},
+			next:   &RaftBlockState{Height: 10, Timestamp: 101},
+			expErr: true,
+		},
+		"equal timestamp": {
+			s:      &RaftBlockState{Height: 10, Timestamp: 100},
+			next:   &RaftBlockState{Height: 11, Timestamp: 100},
+			expErr: true,
+		},
+		"lower timestamp": {
+			s:      &RaftBlockState{Height: 10, Timestamp: 101},
+			next:   &RaftBlockState{Height: 11, Timestamp: 100},
+			expErr: true,
+		},
+		"lower height": {
+			s:      &RaftBlockState{Height: 11, Timestamp: 100},
+			next:   &RaftBlockState{Height: 10, Timestamp: 101},
+			expErr: true,
+		},
+	}
+
+	for name, spec := range specs {
+		t.Run(name, func(t *testing.T) {
+			err := assertValid(spec.s, spec.next)
+			if spec.expErr {
+				require.Error(t, err)
+				return
+			}
+			require.NoError(t, err)
+		})
+	}
+}