diff --git a/src/clint.lua b/src/clint.lua
index c4cd2dd753..dd668d8db4 100755
--- a/src/clint.lua
+++ b/src/clint.lua
@@ -1088,6 +1088,20 @@ local function check_language(filename, clean_lines, linenum, error)
     )
   end
 
+  -- Check for strtol: it silently overflows/truncates and needs error-prone boilerplate.
+  -- TODO: also flag atoi, atol, atoll, strtoul, strtoll, strtoull.
+  local strtol_regex = vim.regex([[\<strtol\>]])
+  if strtol_regex:match_str(line) then
+    error(
+      filename,
+      linenum,
+      'runtime/deprecated',
+      4,
+      'Use getdigits()/getdigits_int() (or vim_str2nr() for non-decimal bases) instead of strtol, '
+        .. 'which overflows silently. See src/nvim/charset.c.'
+    )
+  end
+
   -- Check for memset with wrong argument order: memset(buf, sizeof(buf), 0)
   -- Pattern: memset(arg1, arg2, 0) where arg2 is NOT a valid fill value
   local memset_start = line:find('memset%s*%([^)]*,%s*[^,]*,%s*0%s*%)')
diff --git a/src/nvim/api/command.c b/src/nvim/api/command.c
index cfe87cd641..30cc88ee4a 100644
--- a/src/nvim/api/command.c
+++ b/src/nvim/api/command.c
@@ -463,8 +463,8 @@ String nvim_cmd(uint64_t channel_id, Dict(cmd) *cmd, Dict(cmd_opts) *opts, Arena
         count_value = first_arg.data.integer;
       } else if (first_arg.type == kObjectTypeString) {
         // Try to parse string as a number Example: vim.api.nvim_cmd({cmd = 'copen', args = {'10'}}, {})
-        char *endptr;
-        long val = strtol(first_arg.data.string.data, &endptr, 10);
+        char *endptr = first_arg.data.string.data;
+        long val = getdigits_long(&endptr, false, 0);
         // Check if entire string was consumed (valid number) and string is not empty
         if (*endptr == '\0' && first_arg.data.string.size > 0) {
           is_numeric = true;
diff --git a/src/nvim/eval/window.c b/src/nvim/eval/window.c
index b81951d382..a43d7285f5 100644
--- a/src/nvim/eval/window.c
+++ b/src/nvim/eval/window.c
@@ -9,6 +9,7 @@
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
+#include "nvim/charset.h"
 #include "nvim/cursor.h"
 #include "nvim/errors.h"
 #include "nvim/eval/funcs.h"
@@ -277,8 +278,8 @@ static int get_winnr(tabpage_T *tp, typval_T *argvar)
       }
     } else {
       // Extract the window count (if specified). e.g. winnr('3j')
-      char *endp;
-      int count = (int)strtol(arg, &endp, 10);
+      char *endp = (char *)arg;
+      int count = getdigits_int(&endp, false, 0);
       if (count <= 0) {
         // if count is not specified, default to 1
         count = 1;
diff --git a/src/nvim/file_search.c b/src/nvim/file_search.c
index f0fed217f8..eb13e80290 100644
--- a/src/nvim/file_search.c
+++ b/src/nvim/file_search.c
@@ -407,7 +407,9 @@ void *vim_findfile_init(char *path, char *filename, size_t filenamelen, char *st
         ff_expand_buffer.data[ff_expand_buffer.size++] = *wc_part++;
         ff_expand_buffer.data[ff_expand_buffer.size++] = *wc_part++;
 
-        llevel = strtol(wc_part, &errpt, 10);
+        errpt = wc_part;
+        // Use def=255 so that overflow/too-large values keep the "max expand" behavior.
+        llevel = getdigits(&errpt, false, 255);
         if (errpt != wc_part && llevel > 0 && llevel < 255) {
           ff_expand_buffer.data[ff_expand_buffer.size++] = (char)llevel;
         } else if (errpt != wc_part && llevel == 0) {
diff --git a/src/nvim/highlight_group.c b/src/nvim/highlight_group.c
index 9b893ffaf2..8cda1f7330 100644
--- a/src/nvim/highlight_group.c
+++ b/src/nvim/highlight_group.c
@@ -1478,7 +1478,8 @@ void do_highlight(const char *line, const bool forceit, const bool init)
         // Ignored for now
       } else if (strcmp(key, "BLEND") == 0) {
         if (strcmp(arg, "NONE") != 0) {
-          hl_table[idx].sg_blend = (int)strtol(arg, NULL, 10);
+          char *arg_end = arg;
+          hl_table[idx].sg_blend = getdigits_int(&arg_end, false, 0);
         } else {
           hl_table[idx].sg_blend = -1;
         }
@@ -3182,7 +3183,7 @@ RgbValue name_to_color(const char *name, int *idx)
       && isxdigit((uint8_t)name[6]) && name[7] == NUL) {
     // rgb hex string
     *idx = kColorIdxHex;
-    return (RgbValue)strtol(name + 1, NULL, 16);
+    return (RgbValue)strtol(name + 1, NULL, 16);  // NOLINT(runtime/deprecated)
   } else if (!STRICMP(name, "bg") || !STRICMP(name, "background")) {
     *idx = kColorIdxBg;
     return normal_bg;
diff --git a/src/nvim/indent.c b/src/nvim/indent.c
index 9c0a9d371c..ad83540944 100644
--- a/src/nvim/indent.c
+++ b/src/nvim/indent.c
@@ -67,9 +67,11 @@ bool tabstop_set(char *var, colnr_T **array)
 
   for (char *cp = var; *cp != NUL; cp++) {
     if (cp == var || cp[-1] == ',') {
-      char *end;
+      char *end = cp;
 
-      if (strtol(cp, &end, 10) <= 0) {
+      // Use def=1 so that overflow/too-large values pass this check and are
+      // instead rejected by the "n > TABSTOP_MAX" check in the loop below.
+      if (getdigits(&end, false, 1) <= 0) {
         if (cp != end) {
           emsg(_(e_positive));
         } else {
diff --git a/src/nvim/tui/tui.c b/src/nvim/tui/tui.c
index 96f6494ffd..3a0fd6bbfc 100644
--- a/src/nvim/tui/tui.c
+++ b/src/nvim/tui/tui.c
@@ -14,6 +14,7 @@
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
 #include "nvim/ascii_defs.h"
+#include "nvim/charset.h"
 #include "nvim/cursor_shape.h"
 #include "nvim/event/defs.h"
 #include "nvim/event/loop.h"
@@ -525,14 +526,16 @@ static void terminfo_start(TUIData *tui)
   char *konsolev_env = os_getenv("KONSOLE_VERSION");
   char *term_program_version_env = os_getenv("TERM_PROGRAM_VERSION");
 
-  int vtev = vte_version_env ? (int)strtol(vte_version_env, NULL, 10) : 0;
+  char *vte_version_end = vte_version_env;
+  int vtev = vte_version_env ? getdigits_int(&vte_version_end, false, 0) : 0;
   bool iterm_env = termprg && strstr(termprg, "iTerm.app");
   bool nsterm = (termprg && strstr(termprg, "Apple_Terminal"))
                 || terminfo_is_term_family(term, "nsterm");
   bool konsole = terminfo_is_term_family(term, "konsole")
                  || os_env_exists("KONSOLE_PROFILE_NAME", true)
                  || os_env_exists("KONSOLE_DBUS_SESSION", true);
-  int konsolev = konsolev_env ? (int)strtol(konsolev_env, NULL, 10)
+  char *konsolev_end = konsolev_env;
+  int konsolev = konsolev_env ? getdigits_int(&konsolev_end, false, 0)
                               : (konsole ? 1 : 0);
   bool wezterm = strequal(termprg, "WezTerm");
   const char *weztermv = wezterm ? term_program_version_env : NULL;
diff --git a/test/functional/fixtures/clint_test.c b/test/functional/fixtures/clint_test.c
index dc1eb1bd87..ff960450c3 100644
--- a/test/functional/fixtures/clint_test.c
+++ b/test/functional/fixtures/clint_test.c
@@ -140,6 +140,7 @@ void test_more()
   // Try getenv and setenv
   char *env = getenv("HOME");  // Should trigger runtime/os_fn
   setenv("TEST", "value", 1);   // Should trigger runtime/os_fn
+  long n = strtol(env, NULL, 10);  // Should trigger runtime/deprecated
 }
 
 int main()
diff --git a/test/functional/script/clint_spec.lua b/test/functional/script/clint_spec.lua
index 64e9d5e140..aca1cd2bcb 100644
--- a/test/functional/script/clint_spec.lua
+++ b/test/functional/script/clint_spec.lua
@@ -43,7 +43,8 @@ describe('clint.lua', function()
       'test/functional/fixtures/clint_test.c:138:  Use xfree(...) instead of free(...).  [runtime/memory_fn] [2]',
       'test/functional/fixtures/clint_test.c:141:  Use os_getenv(...) instead of getenv(...).  [runtime/os_fn] [2]',
       'test/functional/fixtures/clint_test.c:142:  Use os_setenv(...) instead of setenv(...).  [runtime/os_fn] [2]',
-      'Total errors found: 28',
+      'test/functional/fixtures/clint_test.c:143:  Use getdigits()/getdigits_int() (or vim_str2nr() for non-decimal bases) instead of strtol, which overflows silently. See src/nvim/charset.c.  [runtime/deprecated] [4]',
+      'Total errors found: 29',
     }
     t.eq(expected, output_lines)
   end)