diff --git a/DESCRIPTION b/DESCRIPTION
index 3ec0b6efb..6a456f3a9 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -21,7 +21,7 @@ License: MIT + file LICENSE
 URL: https://github.com/r-lib/lintr, https://lintr.r-lib.org
 BugReports: https://github.com/r-lib/lintr/issues
 Depends:
-    R (>= 3.5)
+    R (>= 3.6)
 Imports:
     backports (>= 1.1.7),
     codetools,
diff --git a/R/settings.R b/R/settings.R
index cedc289fa..05447ee33 100644
--- a/R/settings.R
+++ b/R/settings.R
@@ -56,7 +56,7 @@ read_config_file <- function(config_file) {
 
   config <- new.env()
   if (endsWith(config_file, ".R")) {
-    load_config <- function(file) sys_source(file, config)
+    load_config <- function(file) sys.source(file, config, keep.source = FALSE, keep.parse.data = FALSE)
     malformed <- function(e) {
       stop("Malformed config file, ensure it is valid R syntax\n  ", conditionMessage(e), call. = FALSE)
     }
@@ -231,10 +231,7 @@ get_encoding_from_dcf <- function(file) {
     warning = function(e) NULL
   )
 
-  if (!is.null(encodings)) {
-    # Produces a warning in R <= 3.5 if encoding is NULL
-    encodings <- encodings[!is.na(encodings)]
-  }
+  encodings <- encodings[!is.na(encodings)]
   if (length(encodings) > 0L) {
     return(encodings[1L])
   }
diff --git a/R/shared_constants.R b/R/shared_constants.R
index de3ac199e..831545b9a 100644
--- a/R/shared_constants.R
+++ b/R/shared_constants.R
@@ -164,7 +164,7 @@ names(infix_metadata) <- c("xml_tag", "string_value")
 # utils::getParseData()'s designation for the tokens wouldn't be valid as XML tags
 infix_metadata$parse_tag <- ifelse(
   startsWith(infix_metadata$xml_tag, "OP-"),
-  quote_wrap(infix_metadata$string_value, "'"),
+  sQuote(infix_metadata$string_value, "'"),
   infix_metadata$xml_tag
 )
 # treated separately because spacing rules are different for unary operators
diff --git a/R/utils.R b/R/utils.R
index b9ee39d9c..6b2e054df 100644
--- a/R/utils.R
+++ b/R/utils.R
@@ -138,9 +138,6 @@ try_silently <- function(expr) {
   )
 }
 
-# imitate sQuote(x, q) [requires R>=3.6]
-quote_wrap <- function(x, q) paste0(q, x, q)
-
 # interface to work like options() or setwd() -- returns the old value for convenience
 set_lang <- function(new_lang) {
   old_lang <- Sys.getenv("LANGUAGE", unset = NA)
diff --git a/R/xp_utils.R b/R/xp_utils.R
index 1a599d727..b48e82c51 100644
--- a/R/xp_utils.R
+++ b/R/xp_utils.R
@@ -9,8 +9,8 @@ xp_text_in_table <- function(table) {
   #   to use "" whenever the string has ' (not a perfect solution). info on
   #   escaping from https://stackoverflow.com/questions/14822153
   single_quoted <- grepl("'", table, fixed = TRUE)
-  table[single_quoted] <- quote_wrap(table[single_quoted], '"')
-  table[!single_quoted] <- quote_wrap(table[!single_quoted], "'")
+  table[single_quoted] <- sQuote(table[single_quoted], '"')
+  table[!single_quoted] <- sQuote(table[!single_quoted], "'")
   return(paste0("text() = ", table, collapse = " or "))
 }
 
diff --git a/R/zzz.R b/R/zzz.R
index 226063c9b..411c7e462 100644
--- a/R/zzz.R
+++ b/R/zzz.R
@@ -282,18 +282,6 @@ default_undesirable_operators <- all_undesirable_operators[names(all_undesirable
 #' @export
 default_settings <- NULL
 
-# TODO(R>=3.6.0): Just use sys.source() directly. Note that we can't
-#   write a wrapper that only passes keep.parse.data=FALSE on R>3.5.0
-#   (without doing some wizardry to evade R CMD check) because
-#   there is a check for arguments not matching the signature which
-#   will throw a false positive on R3.5.0. Luckily the argument
-#   defaults on R>=3.6.0 are dictated by global options, so we can use
-#   that for the wrapper here rather than doing some NSE tricks.
-sys_source <- function(...) {
-  old <- options(keep.source.pkgs = FALSE, keep.parse.data.pkgs = FALSE)
-  on.exit(options(old))
-  sys.source(...)
-}
 settings <- new.env(parent = emptyenv())
 
 # nocov start
@@ -305,18 +293,9 @@ settings <- new.env(parent = emptyenv())
   toset <- !(names(op_lintr) %in% names(op))
   if (any(toset)) options(op_lintr[toset])
 
-  # R>=3.6.0: str2expression, str2lang
   # R>=4.0.0: deparse1
   # R>=4.1.0: ...names
   backports::import(pkgname, c("deparse1", "...names"))
-  base_ns <- getNamespace("base")
-  backports_ns <- getNamespace("backports")
-  lintr_ns <- getNamespace(pkgname)
-  for (base_fun in c("str2lang", "str2expression")) {
-    if (!exists(base_fun, base_ns)) {
-      assign(base_fun, get(base_fun, backports_ns), lintr_ns)
-    }
-  }
 
   utils::assignInMyNamespace("default_settings", list(
     linters = default_linters,
diff --git a/tests/testthat/test-lint_package.R b/tests/testthat/test-lint_package.R
index ae95bdde6..957b8af9c 100644
--- a/tests/testthat/test-lint_package.R
+++ b/tests/testthat/test-lint_package.R
@@ -231,7 +231,6 @@ test_that("package using .lintr.R config lints correctly", {
 })
 
 test_that("lintr need not be attached for .lintr.R configs to use lintr functions", {
-  skip_if_not_r_version("3.6.0") # unclear error message
   exprs <- paste(
     'options(lintr.linter_file = "lintr_test_config")',
     sprintf('lints <- lintr::lint_package("%s")', test_path("dummy_packages", "RConfig")),