diff --git a/R/QueryNamespace.R b/R/QueryNamespace.R
index aa6b1ab..989d945 100644
--- a/R/QueryNamespace.R
+++ b/R/QueryNamespace.R
@@ -14,6 +14,52 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+
+.typeCheckVariable <- function(varName, value, typeStr, isArray) {
+  # Map type strings to checking functions
+  typeChecks <- list(
+    INT = function(x) is.numeric(x) && all(x == as.integer(x)),
+    BIGINT = function(x) is.numeric(x) && all(x %% 1 == 0),
+    CHAR = function(x) is.character(x),
+    VARCHAR = function(x) is.character(x),
+    TEXT = function(x) is.character(x),
+    NUMERIC = function(x) is.numeric(x),
+    BOOLEAN = function (x) is.logical(x) || (is.numeric(x) && all(x %in% c(0, 1)))
+  )
+
+  # Check type exists
+  baseType <- gsub("\\[\\]", "", typeStr)
+  if (!baseType %in% names(typeChecks)) {
+    stop(sprintf("Unknown type check: %s", typeStr))
+  }
+  checkFun <- typeChecks[[baseType]]
+
+  # Check presence
+  if (is.null(value)) {
+    stop(sprintf("Required variable '%s' (type check %s) not supplied to render().", varName, typeStr))
+  }
+  # Check NA
+  if (any(is.na(value))) {
+    stop(sprintf("Variable '%s' (type check %s) contains NA values, which are not allowed.", varName, typeStr))
+  }
+
+  # Array vs scalar
+  if (isArray) {
+    if (!checkFun(value)) {
+      stop(sprintf("Variable '%s' must be an array of type %s.", varName, baseType))
+    }
+    # Must be vector of length >= 1
+    if (!(is.vector(value) && length(value) >= 1)) {
+      stop(sprintf("Variable '%s' must be a non-empty vector of type %s.", varName, baseType))
+    }
+  } else {
+    if (!checkFun(value) || length(value) != 1) {
+      stop(sprintf("Variable '%s' must be a scalar of type %s.", varName, baseType))
+    }
+  }
+}
+
+
 #' QueryNamespace
 #' @export
 #' @description
@@ -174,13 +220,32 @@ QueryNamespace <- R6::R6Class(
     #' @param ... additional variables to be passed to SqlRender::render - will overwrite anything in namespace
     render = function(sql, ...) {
       params <- private$replacementVars$as_list()
-
       addVars <- list(...)
-
       for (k in names(addVars)) {
         params[[k]] <- addVars[[k]]
       }
 
+      # Regex for {TYPEC TYPE[@] @var_name}
+      typecPattern <- "\\{TYPEC\\s+([A-Z]+(\\[\\])?)\\s+@([a-zA-Z0-9_]+)\\}"
+      typecMatches <- gregexpr(typecPattern, sql, perl = TRUE)
+      matchPositions <- regmatches(sql, typecMatches)[[1]]
+
+      if (length(matchPositions) > 0) {
+        for (matchStr in matchPositions) {
+          m <- regexec(typecPattern, matchStr, perl = TRUE)
+          parts <- regmatches(matchStr, m)[[1]]
+          if (length(parts) >= 4) {
+            typeStr <- parts[2]         # e.g. INT, INT[], CHAR, CHAR[], NUMERIC, NUMERIC[]
+            isArray <- grepl("\\[\\]", typeStr)
+            varName <- parts[4]         # <-- Should be parts[4], not parts[3]
+            value <- params[[varName]]
+            .typeCheckVariable(varName, value, typeStr, isArray)
+          }
+        }
+        # Remove all {TYPEC ...} lines from SQL
+        sql <- gsub(typecPattern, "", sql, perl = TRUE)
+      }
+
       params$sql <- sql
       params$warnOnMissingParameters <- FALSE
       do.call(SqlRender::render, params)
diff --git a/man/ResultModelManager-package.Rd b/man/ResultModelManager-package.Rd
index b132006..e8c65b5 100644
--- a/man/ResultModelManager-package.Rd
+++ b/man/ResultModelManager-package.Rd
@@ -12,6 +12,7 @@ Database data model management utilities for R packages in the Observational Hea
 Useful links:
 \itemize{
   \item \url{https://github.com/OHDSI/ResultModelManager}
+  \item \url{https://ohdsi.github.io/ResultModelManager/}
   \item Report bugs at \url{https://github.com/OHDSI/ResultModelManager/issues}
 }
 
diff --git a/tests/testthat/test-QueryNamespace.R b/tests/testthat/test-QueryNamespace.R
index 8341e0c..0b9ecac 100644
--- a/tests/testthat/test-QueryNamespace.R
+++ b/tests/testthat/test-QueryNamespace.R
@@ -128,3 +128,38 @@ test_that("create helper function works", {
     )
   )
 })
+
+
+test_that("render enforces type checks in SQL", {
+  cohortNamespace <- QueryNamespace$new(
+    connectionHandler = connectionHandler,
+    tableSpecification = tableSpecification,
+    result_schema = "main",
+    tablePrefix = "cd_"
+  )
+  on.exit({
+    cohortNamespace$closeConnection()
+  }, add = TRUE)
+
+  # INT scalar OK
+  sql <- "{TYPEC INT @cohort_id} SELECT * FROM @result_schema.@cohort WHERE cohort_definition_id = @cohort_id"
+  expect_error(cohortNamespace$render(sql, cohort_id = 1.5), "scalar of type INT")
+  expect_error(cohortNamespace$render(sql, cohort_id = NA), "contains NA")
+  expect_error(cohortNamespace$render(sql), "not supplied")
+
+  # BIGINT array OK
+  sql <- "{TYPEC BIGINT[] @ids} SELECT * FROM @result_schema.@cohort WHERE cohort_definition_id IN (@ids)"
+  expect_silent(cohortNamespace$render(sql, ids = c(1, 2, 3)))
+  expect_error(cohortNamespace$render(sql, ids = c(1, 2.5)), "array of type BIGINT")
+
+  # CHAR scalar OK
+  sql <- "{TYPEC CHAR @cohort_name} SELECT * FROM @result_schema.@cohort WHERE cohort_name = @cohort_name"
+  expect_silent(cohortNamespace$render(sql, cohort_name = "test"))
+  expect_error(cohortNamespace$render(sql, cohort_name = c("a", "b")), "scalar of type CHAR")
+  expect_error(cohortNamespace$render(sql, cohort_name = NA), "contains NA")
+
+  # CHAR array OK
+  sql <- "{TYPEC CHAR[] @names} SELECT * FROM @result_schema.@cohort WHERE cohort_name IN (@names)"
+  expect_silent(cohortNamespace$render(sql, names = c("a", "b")))
+  expect_error(cohortNamespace$render(sql, names = c("a", NA)), "contains NA")
+})
diff --git a/tests/testthat/test-TypeChecker.R b/tests/testthat/test-TypeChecker.R
new file mode 100644
index 0000000..5f65054
--- /dev/null
+++ b/tests/testthat/test-TypeChecker.R
@@ -0,0 +1,87 @@
+test_that(".typeCheckVariable INT checks", {
+  expect_silent(.typeCheckVariable("x", 1L, "INT", FALSE))
+  expect_silent(.typeCheckVariable("x", 1, "INT", FALSE))
+  expect_error(.typeCheckVariable("x", 1.5, "INT", FALSE), "scalar of type INT")
+  expect_error(.typeCheckVariable("x", NA, "INT", FALSE), "contains NA")
+  expect_error(.typeCheckVariable("x", NULL, "INT", FALSE), "not supplied")
+  expect_error(.typeCheckVariable("x", c(1L, 2L), "INT", FALSE), "scalar of type INT")
+  expect_silent(.typeCheckVariable("x", c(1L, 2L), "INT[]", TRUE))
+  expect_error(.typeCheckVariable("x", c(1.5, 2L), "INT[]", TRUE), "array of type INT")
+  expect_error(.typeCheckVariable("x", numeric(0), "INT[]", TRUE), "non-empty vector")
+})
+
+test_that(".typeCheckVariable BIGINT checks", {
+  expect_silent(.typeCheckVariable("x", 123456789012345, "BIGINT", FALSE))
+  expect_silent(.typeCheckVariable("x", 1e11, "BIGINT", FALSE))
+  expect_silent(.typeCheckVariable("x", 2, "BIGINT", FALSE))
+  expect_error(.typeCheckVariable("x", 1.5, "BIGINT", FALSE), "scalar of type BIGINT")
+  expect_error(.typeCheckVariable("x", NA, "BIGINT", FALSE), "contains NA")
+  expect_error(.typeCheckVariable("x", NULL, "BIGINT", FALSE), "not supplied")
+  expect_error(.typeCheckVariable("x", c(1, 2), "BIGINT", FALSE), "scalar of type BIGINT")
+  expect_silent(.typeCheckVariable("x", c(1, 2, 3), "BIGINT[]", TRUE))
+  expect_error(.typeCheckVariable("x", c(1, 2.5), "BIGINT[]", TRUE), "array of type BIGINT")
+  expect_error(.typeCheckVariable("x", numeric(0), "BIGINT[]", TRUE), "non-empty vector")
+})
+
+test_that(".typeCheckVariable CHAR checks", {
+  expect_silent(.typeCheckVariable("x", "a", "CHAR", FALSE))
+  expect_error(.typeCheckVariable("x", 1, "CHAR", FALSE), "scalar of type CHAR")
+  expect_error(.typeCheckVariable("x", NA_character_, "CHAR", FALSE), "contains NA")
+  expect_error(.typeCheckVariable("x", NULL, "CHAR", FALSE), "not supplied")
+  expect_error(.typeCheckVariable("x", c("a", "b"), "CHAR", FALSE), "scalar of type CHAR")
+  expect_silent(.typeCheckVariable("x", c("a", "b"), "CHAR[]", TRUE))
+  expect_error(.typeCheckVariable("x", c("a", NA_character_), "CHAR[]", TRUE), "contains NA")
+  expect_error(.typeCheckVariable("x", character(0), "CHAR[]", TRUE), "non-empty vector")
+})
+
+test_that(".typeCheckVariable VARCHAR checks", {
+  expect_silent(.typeCheckVariable("x", "hello", "VARCHAR", FALSE))
+  expect_error(.typeCheckVariable("x", 1, "VARCHAR", FALSE), "scalar of type VARCHAR")
+  expect_error(.typeCheckVariable("x", NA_character_, "VARCHAR", FALSE), "contains NA")
+  expect_error(.typeCheckVariable("x", NULL, "VARCHAR", FALSE), "not supplied")
+  expect_error(.typeCheckVariable("x", c("a", "b"), "VARCHAR", FALSE), "scalar of type VARCHAR")
+  expect_silent(.typeCheckVariable("x", c("a", "b"), "VARCHAR[]", TRUE))
+  expect_error(.typeCheckVariable("x", c("a", NA_character_), "VARCHAR[]", TRUE), "contains NA")
+  expect_error(.typeCheckVariable("x", character(0), "VARCHAR[]", TRUE), "non-empty vector")
+})
+
+test_that(".typeCheckVariable TEXT checks", {
+  expect_silent(.typeCheckVariable("x", "some text", "TEXT", FALSE))
+  expect_error(.typeCheckVariable("x", 1, "TEXT", FALSE), "scalar of type TEXT")
+  expect_error(.typeCheckVariable("x", NA_character_, "TEXT", FALSE), "contains NA")
+  expect_error(.typeCheckVariable("x", NULL, "TEXT", FALSE), "not supplied")
+  expect_error(.typeCheckVariable("x", c("a", "b"), "TEXT", FALSE), "scalar of type TEXT")
+  expect_silent(.typeCheckVariable("x", c("a", "b"), "TEXT[]", TRUE))
+  expect_error(.typeCheckVariable("x", c("a", NA_character_), "TEXT[]", TRUE), "contains NA")
+  expect_error(.typeCheckVariable("x", character(0), "TEXT[]", TRUE), "non-empty vector")
+})
+
+test_that(".typeCheckVariable NUMERIC checks", {
+  expect_silent(.typeCheckVariable("x", 3.14, "NUMERIC", FALSE))
+  expect_silent(.typeCheckVariable("x", 1L, "NUMERIC", FALSE))
+  expect_error(.typeCheckVariable("x", "a", "NUMERIC", FALSE), "scalar of type NUMERIC")
+  expect_error(.typeCheckVariable("x", NA, "NUMERIC", FALSE), "contains NA")
+  expect_error(.typeCheckVariable("x", NULL, "NUMERIC", FALSE), "not supplied")
+  expect_error(.typeCheckVariable("x", c(1, 2), "NUMERIC", FALSE), "scalar of type NUMERIC")
+  expect_silent(.typeCheckVariable("x", c(1.1, 2.2, 3.3), "NUMERIC[]", TRUE))
+  expect_error(.typeCheckVariable("x", c(1.1, NA), "NUMERIC[]", TRUE), "contains NA")
+  expect_error(.typeCheckVariable("x", numeric(0), "NUMERIC[]", TRUE), "non-empty vector")
+})
+
+test_that(".typeCheckVariable BOOLEAN checks", {
+  expect_silent(.typeCheckVariable("x", TRUE, "BOOLEAN", FALSE))
+  expect_silent(.typeCheckVariable("x", FALSE, "BOOLEAN", FALSE))
+  expect_silent(.typeCheckVariable("x", 1, "BOOLEAN", FALSE))
+  expect_silent(.typeCheckVariable("x", 0, "BOOLEAN", FALSE))
+  expect_error(.typeCheckVariable("x", NA, "BOOLEAN", FALSE), "contains NA")
+  expect_error(.typeCheckVariable("x", NULL, "BOOLEAN", FALSE), "not supplied")
+  expect_error(.typeCheckVariable("x", c(TRUE, FALSE), "BOOLEAN", FALSE), "scalar of type BOOLEAN")
+  expect_silent(.typeCheckVariable("x", c(TRUE, FALSE), "BOOLEAN[]", TRUE))
+  expect_silent(.typeCheckVariable("x", c(TRUE, 1, 0), "BOOLEAN[]", TRUE))
+  expect_error(.typeCheckVariable("x", c(TRUE, NA), "BOOLEAN[]", TRUE), "contains NA")
+  expect_error(.typeCheckVariable("x", logical(0), "BOOLEAN[]", TRUE), "non-empty vector")
+})
+
+test_that(".typeCheckVariable unknown type", {
+  expect_error(.typeCheckVariable("x", 1, "UNKNOWN", FALSE), "Unknown type check")
+})
\ No newline at end of file