diff --git a/DESCRIPTION b/DESCRIPTION
index d20c188..0715f40 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -2,7 +2,7 @@ Encoding: UTF-8
 Package: optparse
 Type: Package
 Title: Command Line Option Parser
-Version: 1.8.0-4
+Version: 1.8.0-5
 Authors@R: c(person("Trevor L.", "Davis", role=c("aut", "cre"),
              email="trevor.l.davis@gmail.com",
              comment = c(ORCID = "0000-0001-6341-4639")),
diff --git a/NEWS.md b/NEWS.md
index 38ea671..754fc75 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -4,16 +4,18 @@ optparse 1.8.0 (development)
 New features
 ------------
 
-* `make_option()` (and `add_option()`) now support the following new actions (#22):
+* `add_option()` (and `make_option()`) now support the following new actions (#22):
 
   + `action = "append"` which appends each occurrence's value to `default`.
   + `action = "append_const"` which appends `const` to `default` each time the flag is seen.
   + `action = "count"`, which counts the number of times a flag is seen and adds it to `default` (treated as `0L` if not supplied). Returns `NULL` if the flag is never seen and no `default` was supplied.
   + `action = "store_const"` which stores `const` when the flag is seen.
 
-* `make_option()` (and `add_option()`) now support a `const` parameter (intended for new actions `"append_const"` and `"store_const"`).
+* `add_option()` (and `make_option()`) now support a `const` parameter (intended for new actions `"append_const"` and `"store_const"`).
 
-* `make_option()` (and `add_option()`) now support a `required` argument.
+* `add_option()` (and `make_option()`) now allow non-letter characters in short flags (e.g., `-1`) and at the beginning of long flags (e.g., `--1flag`), following Python's `optparse` convention. However long and short flags may not contain `=` or whitespace (or begin with hyphens).
+
+* `add_option()` (and `make_option()`) now support a `required` argument.
   If `TRUE`, `parse_args()` will throw an error if the option is not provided on the command line (#17).
 
 Bug fixes and minor improvements
diff --git a/R/optparse.R b/R/optparse.R
index 4355e88..2cb35c3 100644
--- a/R/optparse.R
+++ b/R/optparse.R
@@ -44,7 +44,6 @@
 #' @slot formatter  A function that [print_help()] will use to print out after
 #'     the options statement.  Default is [IndentedHelpFormatter()].  This
 #'     package also provides the builtin formatter [TitledHelpFormatter()].
-#' @author Trevor Davis.
 #' @seealso [OptionParserOption]
 #' @import methods
 #' @exportClass OptionParser
@@ -97,9 +96,9 @@ setMethod("options<-", "OptionParser", function(x, value) {
 #' Class to hold information about command-line options
 #'
 #' @slot short_flag String of the desired short flag
-#'     comprised of the \dQuote{-} followed by a letter.
-#' @slot long_flag String of the desired long flag comprised of \dQuote{--}
-#'     followed by a letter and then a sequence of alphanumeric characters.
+#'     comprised of the `-` followed by a single non-dash character (but not `=` or a whitespace character).
+#' @slot long_flag String of the desired long flag comprised of `--`
+#'     followed by a non-dash character and then (optionally) more characters (but not any `=` or whitespace characters).
 #' @slot action `r ro_action`
 #' @slot type `r ro_type`
 #' @slot dest `r ro_dest`
@@ -160,7 +159,6 @@ OptionParserOption <- setClass(
 #'                  Default is [IndentedHelpFormatter()].
 #'                  The other builtin formatter provided by this package is [TitledHelpFormatter()].
 #' @return An instance of the `OptionParser` class.
-#' @author Trevor Davis.
 #'
 #' @seealso [parse_args()] [make_option()] [add_option()]
 #' @references Python's `optparse` library, which inspired this package,
@@ -219,9 +217,9 @@ OptionParser <- function(
 #' @rdname add_make_option
 #' @param object An instance of the `OptionParser` class
 #' @param opt_str A character vector containing the string of the desired long
-#'     flag comprised of \dQuote{--} followed by a letter and then a sequence of
-#'     alphanumeric characters and optionally a string of the desired short flag
-#'     comprised of the \dQuote{-} followed by a letter.
+#'     flag comprised of `--` followed by a non-dash character (and optionally more characters), and
+#'     optionally a string of the desired short flag comprised of the
+#'     `-` followed by a single non-dash character.  We don't allow `=` or whitespace characters in flags.
 #' @param action `r ro_action`
 #' @param type `r ro_type`
 #' @param dest `r ro_dest`
@@ -234,7 +232,6 @@ OptionParser <- function(
 #' @param callback_args `r ro_callback_args`
 #' @return Both [make_option()] and [add_option()] return instances of
 #'     class `OptionParserOption`.
-#' @author Trevor Davis.
 #'
 #' @seealso [parse_args()] [OptionParser()]
 #' @references Python's `optparse` library, which inspires this package,
@@ -278,18 +275,34 @@ make_option <- function(
 	action <- ifelse(is.null(action), ifelse(is.null(callback), "store", "callback"), action)
 
 	# flags
-	short_flag <- opt_str[grepl("^-[[:alpha:]]", opt_str)]
+	short_flag <- opt_str[grepl("^-[^-]", opt_str)]
 	if (length(short_flag) == 0) {
 		short_flag <- NA_character_
 	} else {
 		if (nchar(short_flag) > 2) {
-			stop(paste("Short flag", short_flag, "must only be a '-' and a single letter"))
+			stop(paste(
+				"Short flag",
+				short_flag,
+				"must only be a '-' and a single non-dash character"
+			))
+		}
+		if (grepl("[[:space:]]", short_flag)) {
+			stop(paste("Short flag", short_flag, "must not contain whitespace"))
+		}
+		if (grepl("=", short_flag, fixed = TRUE)) {
+			stop(paste("Short flag", short_flag, "must not contain '='"))
 		}
 	}
-	long_flag <- opt_str[grepl("^--[[:alpha:]]", opt_str)]
+	long_flag <- opt_str[grepl("^--[^-]", opt_str)]
 	if (length(long_flag) == 0) {
 		stop("We require a long flag option")
 	}
+	if (grepl("=", long_flag, fixed = TRUE)) {
+		stop(paste("Long flag", long_flag, "must not contain '='"))
+	}
+	if (grepl("[[:space:]]", long_flag)) {
+		stop(paste("Long flag", long_flag, "must not contain whitespace"))
+	}
 
 	# type
 	if (is.null(type)) {
@@ -414,7 +427,6 @@ add_option <- function(
 #' @param object A `OptionParser` instance.
 #' @return [print_help()] uses the `cat` function to print out a usage
 #' message.  It returns `invisible(NULL)`.
-#' @author Trevor Davis.
 #'
 #' @seealso [parse_args()] [OptionParser()]
 #' @references Python's `optparse` library, which inspired this package,
@@ -560,7 +572,6 @@ as_string <- function(default) {
 #'     Jonas Zimmermann for bug report; Miroslav Posta for bug reports;
 #'     Stefan Seemayer for bug report and patch;
 #'     Kirill \enc{Müller}{Muller} for patches; Steve Humburg for patch.
-#' @author Trevor Davis.
 #'
 #' @seealso [OptionParser()] [print_help()]
 #' @references Python's `optparse` library, which inspired this package,
diff --git a/man/OptionParser-class.Rd b/man/OptionParser-class.Rd
index c397f73..2c3f9cd 100644
--- a/man/OptionParser-class.Rd
+++ b/man/OptionParser-class.Rd
@@ -34,6 +34,3 @@ package also provides the builtin formatter \code{\link[=TitledHelpFormatter]{Ti
 \seealso{
 \link{OptionParserOption}
 }
-\author{
-Trevor Davis.
-}
diff --git a/man/OptionParser.Rd b/man/OptionParser.Rd
index 99d059f..cb207f2 100644
--- a/man/OptionParser.Rd
+++ b/man/OptionParser.Rd
@@ -59,6 +59,3 @@ is described here: \url{https://docs.python.org/3/library/optparse.html}
 \seealso{
 \code{\link[=parse_args]{parse_args()}} \code{\link[=make_option]{make_option()}} \code{\link[=add_option]{add_option()}}
 }
-\author{
-Trevor Davis.
-}
diff --git a/man/OptionParserOption-class.Rd b/man/OptionParserOption-class.Rd
index 603a803..a0e7785 100644
--- a/man/OptionParserOption-class.Rd
+++ b/man/OptionParserOption-class.Rd
@@ -12,10 +12,10 @@ Class to hold information about command-line options
 
 \describe{
 \item{\code{short_flag}}{String of the desired short flag
-comprised of the \dQuote{-} followed by a letter.}
+comprised of the \code{-} followed by a single non-dash character (but not \code{=} or a whitespace character).}
 
-\item{\code{long_flag}}{String of the desired long flag comprised of \dQuote{--}
-followed by a letter and then a sequence of alphanumeric characters.}
+\item{\code{long_flag}}{String of the desired long flag comprised of \verb{--}
+followed by a non-dash character and then (optionally) more characters (but not any \code{=} or whitespace characters).}
 
 \item{\code{action}}{A character string describing the action \code{optparse} should take when it encounters an option. One of:
 \itemize{
diff --git a/man/add_make_option.Rd b/man/add_make_option.Rd
index 98d8f14..ebc7704 100644
--- a/man/add_make_option.Rd
+++ b/man/add_make_option.Rd
@@ -37,9 +37,9 @@ add_option(
 }
 \arguments{
 \item{opt_str}{A character vector containing the string of the desired long
-flag comprised of \dQuote{--} followed by a letter and then a sequence of
-alphanumeric characters and optionally a string of the desired short flag
-comprised of the \dQuote{-} followed by a letter.}
+flag comprised of \verb{--} followed by a non-dash character (and optionally more characters), and
+optionally a string of the desired short flag comprised of the
+\code{-} followed by a single non-dash character.  We don't allow \code{=} or whitespace characters in flags.}
 
 \item{action}{A character string describing the action \code{optparse} should take when it encounters an option. One of:
 \itemize{
@@ -122,6 +122,3 @@ is described here: \url{https://docs.python.org/3/library/optparse.html}
 \seealso{
 \code{\link[=parse_args]{parse_args()}} \code{\link[=OptionParser]{OptionParser()}}
 }
-\author{
-Trevor Davis.
-}
diff --git a/man/parse_args.Rd b/man/parse_args.Rd
index d9d1976..0cc94f4 100644
--- a/man/parse_args.Rd
+++ b/man/parse_args.Rd
@@ -109,6 +109,3 @@ is described here: \url{https://docs.python.org/3/library/optparse.html}
 \seealso{
 \code{\link[=OptionParser]{OptionParser()}} \code{\link[=print_help]{print_help()}}
 }
-\author{
-Trevor Davis.
-}
diff --git a/man/print_help.Rd b/man/print_help.Rd
index 0143d9e..b74c5c5 100644
--- a/man/print_help.Rd
+++ b/man/print_help.Rd
@@ -24,6 +24,3 @@ is described here: \url{https://docs.python.org/3/library/optparse.html}
 \seealso{
 \code{\link[=parse_args]{parse_args()}} \code{\link[=OptionParser]{OptionParser()}}
 }
-\author{
-Trevor Davis.
-}
diff --git a/tests/testthat/_snaps/optparse.md b/tests/testthat/_snaps/optparse.md
index f71d671..4ba57c0 100644
--- a/tests/testthat/_snaps/optparse.md
+++ b/tests/testthat/_snaps/optparse.md
@@ -6,6 +6,38 @@
       Error in `make_option()`:
       ! We require a long flag option
 
+---
+
+    Code
+      make_option("- ")
+    Condition
+      Error in `make_option()`:
+      ! Short flag -  must not contain whitespace
+
+---
+
+    Code
+      make_option("-=")
+    Condition
+      Error in `make_option()`:
+      ! Short flag -= must not contain '='
+
+---
+
+    Code
+      make_option("--fo=o")
+    Condition
+      Error in `make_option()`:
+      ! Long flag --fo=o must not contain '='
+
+---
+
+    Code
+      make_option("--fo o")
+    Condition
+      Error in `make_option()`:
+      ! Long flag --fo o must not contain whitespace
+
 # `required` argument works as expected
 
     Code
diff --git a/tests/testthat/test-optparse.R b/tests/testthat/test-optparse.R
index 870d5d6..795305c 100644
--- a/tests/testthat/test-optparse.R
+++ b/tests/testthat/test-optparse.R
@@ -67,6 +67,13 @@ test_that("`make_option()` works as expected", {
 	expect_equal(make_option("--filename")@type, "character")
 	expect_snapshot(error = TRUE, make_option("badflag"))
 	expect_error(make_option("-cd"), "must only be")
+	expect_equal(make_option(c("-1", "--one"))@short_flag, "-1")
+	expect_equal(make_option("--1flag")@long_flag, "--1flag")
+	expect_equal(make_option("--add-numbers")@long_flag, "--add-numbers")
+	expect_snapshot(error = TRUE, make_option("- "))
+	expect_snapshot(error = TRUE, make_option("-="))
+	expect_snapshot(error = TRUE, make_option("--fo=o"))
+	expect_snapshot(error = TRUE, make_option("--fo o"))
 })
 
 get_long_flags <- function(parser) {