diff --git a/src/builtin.cpp b/src/builtin.cpp
index 658722bc4..2e2d35a1c 100644
--- a/src/builtin.cpp
+++ b/src/builtin.cpp
@@ -1588,8 +1588,8 @@ int builtin_function(parser_t &parser, io_streams_t &streams, const wcstring_lis
                         e.param1.job_id = job_id;
                     }
                 } else {
-                    pid_t pid;
-                    if (!(parse_integer(w.woptarg, &pid)) || pid < 1) {
+                    pid_t pid = wcstoimax(w.woptarg, &end, 10);
+                    if (pid < 1 || !(*w.woptarg != L'\0' && *end == L'\0')) {
                         append_format(*out_err, _(L"%ls: Invalid process id '%ls'"), argv[0],
                                       w.woptarg);
                         res = STATUS_BUILTIN_ERROR;
diff --git a/src/common.h b/src/common.h
index 50100af8b..2bdf3e3ae 100644
--- a/src/common.h
+++ b/src/common.h
@@ -11,9 +11,6 @@
 #include <string.h>
 #include <sys/types.h>
 #include <termios.h>
-#include <stddef.h>
-#include <limits>
-#include <inttypes.h>
 #include <wchar.h>
 #include <memory>
 #include <sstream>
@@ -674,21 +671,6 @@ ssize_t read_loop(int fd, void *buff, size_t count);
 void __attribute__((noinline)) debug(int level, const char *msg, ...);
 void __attribute__((noinline)) debug(int level, const wchar_t *msg, ...);
 
-/// Parse an integer and check limits for type
-/// The only way to be safe from overflows is intmax_t.
-/// Do that, and make sure the result isn't bigger than the maximum supported for whatever type.
-template <typename T>
-bool parse_integer(const wchar_t *in, T* out) {
-  wchar_t *end;
-  intmax_t res = wcstoimax(in, &end, 0);
-
-  if (!(*in != L'\0' && *end == L'\0')) return false;
-  if (std::numeric_limits<T>::max() < res || res < std::numeric_limits<T>::min()) return false;
-
-  *out = static_cast<T>(res);
-  return true;
-}
-
 /// Replace special characters with backslash escape sequences. Newline is replaced with \n, etc.
 ///
 /// \param in The string to be escaped