diff --git a/pkg/rpc/client/rpc.go b/pkg/rpc/client/rpc.go
index d0bca2474..0d8ca01ff 100644
--- a/pkg/rpc/client/rpc.go
+++ b/pkg/rpc/client/rpc.go
@@ -489,7 +489,7 @@ func (c *Client) CalculateValidUntilBlock() (uint32, error) {
 			expiresAt:       blockCount + cacheTimeout,
 		}
 	}
-	return blockCount + validatorsCount, nil
+	return blockCount + validatorsCount + 1, nil
 }
 
 // AddNetworkFee adds network fee for each witness script and optional extra
diff --git a/pkg/rpc/client/rpc_test.go b/pkg/rpc/client/rpc_test.go
index 5845b3065..8fea9d613 100644
--- a/pkg/rpc/client/rpc_test.go
+++ b/pkg/rpc/client/rpc_test.go
@@ -1321,14 +1321,14 @@ func TestCalculateValidUntilBlock(t *testing.T) {
 
 	validUntilBlock, err := c.CalculateValidUntilBlock()
 	assert.NoError(t, err)
-	assert.Equal(t, uint32(54), validUntilBlock)
+	assert.Equal(t, uint32(55), validUntilBlock)
 	assert.Equal(t, 1, getBlockCountCalled)
 	assert.Equal(t, 1, getValidatorsCalled)
 
 	// check, whether caching is working
 	validUntilBlock, err = c.CalculateValidUntilBlock()
 	assert.NoError(t, err)
-	assert.Equal(t, uint32(54), validUntilBlock)
+	assert.Equal(t, uint32(55), validUntilBlock)
 	assert.Equal(t, 2, getBlockCountCalled)
 	assert.Equal(t, 1, getValidatorsCalled)
 }