diff --git a/R/MergeRefToExp.R b/R/MergeRefToExp.R
index 365ceb51178df6135dce1ea09956d7b4f1a0f1d8..a5cfc206b46aa5e5de2c4193ca3f0657309925af 100644
--- a/R/MergeRefToExp.R
+++ b/R/MergeRefToExp.R
@@ -143,10 +143,14 @@ MergeRefToExp <- function(data1, dates1, start1, end1, data2, dates2, start2, en
     names(dim(data2)) <- time_dim
   }
   if (is.null(dim(dates1))) {
+    warning("Dimensions in 'dates1' element are missed and ",
+                "all data would be used.")
     dim(dates1) <- length(dates1)
     names(dim(dates1)) <- time_dim
   }
   if (is.null(dim(dates2))) {
+    warning("Dimensions in 'dates2' element are missed and ",
+                "all data would be used.")
     dim(dates2) <- length(dates2)
     names(dim(dates2)) <- time_dim
   }
diff --git a/R/SelectPeriodOnData.R b/R/SelectPeriodOnData.R
index a6f9c295a37dd5c2e4051ec5a9d42b14dee1231f..85b7ff33d7d3a35e0a95df96f1fcab636df1faca 100644
--- a/R/SelectPeriodOnData.R
+++ b/R/SelectPeriodOnData.R
@@ -121,6 +121,11 @@ SelectPeriodOnData <- function(data, dates, start, end,
     res <- Apply(list(data, res), target_dims = time_dim,
                  fun = function(x, y) {
                     res <- x[y]
+                    if (is.null(dim(res))) {
+                      dim(res) <- 1
+                      names(dim(res)) <- time_dim
+                    }
+                    return(res)
                  }, output_dims = time_dim, ncores = ncores)$output1 
   }
   return(res)
diff --git a/tests/testthat/test-MergeRefToExp.R b/tests/testthat/test-MergeRefToExp.R
index a74df9036afb1fe82b70265012269ed9fbf1de64..b4503d86f34abf8c1348f4dafc7cd82dedc32d46 100644
--- a/tests/testthat/test-MergeRefToExp.R
+++ b/tests/testthat/test-MergeRefToExp.R
@@ -11,25 +11,81 @@ test_that("Sanity checks", {
                    as.Date("01-12-1994", "%d-%m-%Y", tz = 'UTC'), "day")
   dim(ref_dates) <- c(ftime = 350, sdate = 2)
   ref <- array(1001:1700, c(ftime = 350, sdate = 2))
-  data <- array(1:(2*154*2), c(ftime = 154, sdate = 2, member= 2))
+  data <- array(1:(2 * 154 * 2), c(ftime = 154, sdate = 2, member= 2))
+
+suppressWarnings(
   ref <- CSTools::s2dv_cube(data = ref, Dates = list(start = ref_dates,
                                                    end = ref_dates))
+)
+suppressWarnings(
   data <- CSTools::s2dv_cube(data = data, Dates = list(start = data_dates,
                                             end = data_dates))
-  
+)
+suppressWarnings(
   expect_equal(CST_MergeRefToExp(data1 = ref, data2 = data, start1 = list(21, 6),
                                  end1 = list(30, 6), start2 = list(1, 7),  
                                  end2 = list(21, 9))$Dates, 
                SelectPeriodOnDates(ref_dates, start = list(21, 6), end = list(21,9)))
+)
 
   output <- array(c(1172:1181, 1:83, 1537:1546, 155:237, 1172:1181, 309:391,
                     1537:1546, 463:545), c(ftime = 93, sdate = 2, member = 2)) 
 
+suppressWarnings(
   expect_equal(CST_MergeRefToExp(data1 = ref, data2 = data, start1 = list(21, 6),
                                  end1 = list(30, 6), start2 = list(1, 7),
                                  end2 = list(21, 9))$data, 
                output)
- })
+)
+
+  # issue 13: One lead time
+  data_dates <- c(as.Date("01-06-1993", "%d-%m-%Y", tz = 'UTC'),
+                      as.Date("01-07-1993", "%d-%m-%Y", tz = 'UTC'),
+                  as.Date("01-06-1994", "%d-%m-%Y", tz = 'UTC'),
+                      as.Date("01-07-1994","%d-%m-%Y", tz = 'UTC'))
+
+  dim(data_dates) <- c(ftime = 2, sdate = 2)
+  ref_dates <- c(as.Date("01-05-1993", "%d-%m-%Y", tz = 'UTC'),
+                 as.Date("01-05-1994", "%d-%m-%Y", tz = 'UTC'))
+  dim(ref_dates) <- c(ftime = 1, sdate = 2)
+  ref <- array(1:2, c(ftime = 1, sdate = 2))
+  data <- array(1:(2 * 3 * 2), c(ftime = 2, sdate = 2, member = 3))
+
+suppressWarnings(
+  ref <- CSTools::s2dv_cube(data = ref, Dates = list(start = ref_dates,
+                                                   end = ref_dates))
+)
+suppressWarnings(
+  data <- CSTools::s2dv_cube(data = data, Dates = list(start = data_dates,
+                                            end = data_dates))
+)
+  res_dates <- c(as.Date("01-05-1993", "%d-%m-%Y", tz = 'UTC'),
+                 as.Date("01-06-1993", "%d-%m-%Y", tz = 'UTC'),
+                 as.Date("01-07-1993", "%d-%m-%Y", tz = 'UTC'),
+                 as.Date("01-05-1994", "%d-%m-%Y", tz = 'UTC'),
+                 as.Date("01-06-1994", "%d-%m-%Y", tz = 'UTC'),
+                 as.Date("01-07-1994","%d-%m-%Y", tz = 'UTC'))
+  dim(res_dates) <- c(ftime = 3, sdate = 2)
+
+suppressWarnings(
+  expect_equal(CST_MergeRefToExp(data1 = ref, data2 = data, start1 = list(1, 5),
+                                 end1 = list(31, 5), start2 = list(1, 6),
+                                 end2 = list(31, 7))$Dates,
+               res_dates)
+)
+
+  output <- abind::abind(t(matrix(rep(1:2, 3), ncol = 2, nrow = 3, byrow = T)),
+                         data$data, along = 1)
+  names(dim(output)) <- c('ftime', 'sdate', 'member')
+
+suppressWarnings(
+  expect_equal(CST_MergeRefToExp(data1 = ref, data2 = data, start1 = list(1, 5),
+                                 end1 = list(31, 5), start2 = list(1, 6),
+                                 end2 = list(31, 7))$data,
+               output)
+)
+
+})
 
 test_that("Seasonal", {
 
@@ -49,22 +105,32 @@ test_that("Seasonal", {
   dim(dates) <- dim.dates
 
   ref <- array(1:(215*25), c(ftime = 215, sdate = 25))
+
+suppressWarnings(
   ref <- CSTools::s2dv_cube(data = ref, 
                             Dates = list(start = dates,
                                          end = dates))
+)
 
   data <- array(1:(215*25*3), c(ftime = 215, sdate = 25, member=3))
+
+suppressWarnings(
   data <- CSTools::s2dv_cube(data = data, 
                              Dates = list(start = dates,
                                          end = dates))
+)
 
+suppressWarnings(
   expect_equal(CST_MergeRefToExp(data1 = data, data2 = ref, start1 = list(21, 6),
                                  end1 = list(30, 6), start2 = list(1, 7),  
                                  end2 = list(21, 9))$Dates, 
                SelectPeriodOnDates(dates, start = list(21, 6), end = list(21,9)))
+)
   
+suppressWarnings(  
   expect_equal(CST_MergeRefToExp(data1 = ref, data2 = data, start1 = list(21, 6),
                                  end1 = list(30, 6), start2 = list(1, 7),  
                                  end2 = list(21, 9))$Dates, 
                SelectPeriodOnDates(dates, start = list(21, 6), end = list(21,9)))
+)
 })