diff --git a/R/fit.R b/R/fit.R
index 326e642ae..c59da9479 100644
--- a/R/fit.R
+++ b/R/fit.R
@@ -709,6 +709,8 @@ sdmTMB <- function(
   if (!is.null(time)) {
     assert_that(time %in% names(data),
       msg = "Specified `time` column is missing from `data`.")
+    assert_that(sum(is.na(as.numeric(data[[time]]))) == 0L,
+      msg = "Specified `time` column can't be coerced to a numeric value or contains NAs. Please remove any NAs in the time column.")
   }
   if (is.null(time)) {
     time <- "_sdmTMB_time"
diff --git a/tests/testthat/test-2-fit-less-basic.R b/tests/testthat/test-2-fit-less-basic.R
index 00adf561e..40d0d2944 100644
--- a/tests/testthat/test-2-fit-less-basic.R
+++ b/tests/testthat/test-2-fit-less-basic.R
@@ -507,3 +507,15 @@ test_that("sdmTMB throws error on AR1/RW with non-numeric time", {
       mesh = pcod_mesh_2011
     ))
 })
+
+test_that("Time with an NA gets flagged", {
+  skip_on_cran()
+  d <- pcod_2011
+  d$yr <- as.character(d$year)
+  d$yr[2] <- NA
+  expect_error({
+    m <- sdmTMB(density ~ 1, time = "yr", spatial = "off", spatiotemporal = "off", data = d)
+  }, regexp = "time")
+})
+
+