diff --git a/configure.sh b/configure.sh
index 93c96a9c..964b1204 100755
--- a/configure.sh
+++ b/configure.sh
@@ -9,7 +9,6 @@
 #
 ac_help='--enable-amalloc	Enable memory allocation debugging
 --with-tabstops=N	Set tabstops to N characters (default is 4)
---with-github-tags	Allow `_` and `-` in <> tags
 --with-urlencoded-anchor	Use url-encoded chars to multibyte chars in toc links
 --enable-all-features	Turn on all stable optional features
 --shared		Build shared libraries (default is static)'
@@ -45,14 +44,13 @@ TARGET=markdown
 
 AC_INIT $TARGET
 
-for banned_with in dl fenced-code id-anchor; do
+for banned_with in dl fenced-code id-anchor github-tags; do
     banned_with_variable_ref=\$WITH_`echo "$banned_with" | $AC_UPPERCASE | tr - _`
     if [ "`eval echo "$banned_with_variable_ref"`" ]; then
 	AC_FAIL "Invalid option: --with-$banned_with. Please use a runtime flag to configure this feature."
     fi
 done
 
-test "$WITH_GITHUB_TAGS" && AC_DEFINE 'WITH_GITHUB_TAGS' 1
 test "$WITH_URLENCODED_ANCHOR" && AC_DEFINE 'WITH_URLENCODED_ANCHOR' 1
 test "$DEBIAN_GLITCH" && AC_DEFINE 'DEBIAN_GLITCH' 1
 
diff --git a/flags.c b/flags.c
index 53717d54..3b12797e 100644
--- a/flags.c
+++ b/flags.c
@@ -34,6 +34,7 @@ static struct flagnames flagnames[] = {
     { MKD_DLEXTRA,        "DLEXTRA" },
     { MKD_FENCEDCODE,     "FENCEDCODE" },
     { MKD_IDANCHOR,       "IDANCHOR" },
+    { MKD_GITHUBTAGS,     "GITHUBTAGS" },
 };
 #define NR(x)	(sizeof x/sizeof x[0])
 
diff --git a/generate.c b/generate.c
index a91949ea..888eeea8 100644
--- a/generate.c
+++ b/generate.c
@@ -1009,11 +1009,9 @@ maybe_tag_or_link(MMIOT *f)
 	}
 	else if ( isspace(c) )
 	    break;
-#if WITH_GITHUB_TAGS
-	else if ( ! (c == '/' || c == '-' || c == '_' || isalnum(c) ) )
-#else
-	else if ( ! (c == '/' || isalnum(c) ) )
-#endif
+	else if ( ! (c == '/'
+		     || (f->flags & MKD_GITHUBTAGS && (c == '-' || c == '_'))
+		     || isalnum(c) ) )
 	    maybetag=0;
     }
 
diff --git a/markdown.1 b/markdown.1
index b31ab096..eded7f49 100644
--- a/markdown.1
+++ b/markdown.1
@@ -123,6 +123,8 @@ Extract <style> blocks from the output.
 Allow fenced code blocks (not default).
 .It Ar idanchor
 Use id= anchors for table-of-contents links instead of <a name=/> (not default).
+.It Ar githubtags
+Allow underscore and dash in passed through element names (not default).
 .El
 .Pp
 As an example, the option
diff --git a/markdown.3 b/markdown.3
index 9e9ac5c5..f60fc62a 100644
--- a/markdown.3
+++ b/markdown.3
@@ -116,6 +116,8 @@ Do not extract (omit) <style/> blocks from the output.
 Allow fenced code blocks.
 .It Ar MKD_IDANCHOR
 Use id= anchors instead of <a name=/> for table-of-contents links.
+.It Ar MKD_GITHUBTAGS
+Allow underscore and dash in passed through element names.
 .El
 .Sh RETURN VALUES
 .Fn markdown
diff --git a/markdown.h b/markdown.h
index 51ed602c..6cfcc3d2 100644
--- a/markdown.h
+++ b/markdown.h
@@ -133,8 +133,9 @@ typedef struct mmiot {
 #define	MKD_DLEXTRA	0x01000000
 #define MKD_FENCEDCODE	0x02000000
 #define MKD_IDANCHOR	0x04000000
-#define IS_LABEL	0x08000000
-#define USER_FLAGS	0x0FFFFFFF
+#define MKD_GITHUBTAGS	0x08000000
+#define IS_LABEL	0x40000000
+#define USER_FLAGS	0x7FFFFFFF
 #define INPUT_MASK	(MKD_NOHEADER|MKD_TABSTOP)
 
     Callback_data *cb;
diff --git a/mkdio.h.in b/mkdio.h.in
index 51ba87fe..0899af1f 100644
--- a/mkdio.h.in
+++ b/mkdio.h.in
@@ -110,6 +110,7 @@ void mkd_ref_prefix(MMIOT*, char*);
 #define	MKD_DLEXTRA	0x01000000	/* enable extra-style definition lists */
 #define MKD_FENCEDCODE	0x02000000	/* enabled fenced code blocks */
 #define MKD_IDANCHOR	0x04000000	/* use id= anchors for TOC links */
+#define MKD_GITHUBTAGS	0x08000000	/* allow dash and underscore in element names */
 
 #define MKD_EMBED	MKD_NOLINKS|MKD_NOIMAGE|MKD_TAGTEXT
 
diff --git a/pgm_options.c b/pgm_options.c
index d25bfe5a..8a66c163 100644
--- a/pgm_options.c
+++ b/pgm_options.c
@@ -59,6 +59,7 @@ static struct _opt {
     { "dlextra",       "extra-style definition lists", 0, 0, 1, MKD_DLEXTRA },
     { "fencedcode",    "fenced code blocks",         0, 0, 1, MKD_FENCEDCODE },
     { "idanchor",      "id= anchors in TOC",         0, 0, 1, MKD_IDANCHOR },
+    { "githubtags",    "permit - and _ in element names", 0, 0, 0, MKD_GITHUBTAGS },
 } ;
 
 #define NR(x)	(sizeof x / sizeof x[0])
diff --git a/tests/githubtags.t b/tests/githubtags.t
new file mode 100644
index 00000000..6990a661
--- /dev/null
+++ b/tests/githubtags.t
@@ -0,0 +1,23 @@
+. tests/functions.sh
+
+title "github tags"
+
+rc=0
+MARKDOWN_FLAGS=
+
+SRC='<element-name>content</element-name>'
+
+try 'github tags disabled by default' \
+"$SRC" \
+'<p>&lt;element-name>content&lt;/element-name></p>'
+
+try -fgithubtags 'github tags' \
+"$SRC" \
+'<p><element-name>content</element-name></p>'
+
+try 'normal tags pass through' \
+'<a>sdf</a>' \
+'<p><a>sdf</a></p>'
+
+summary $0
+exit $rc
diff --git a/version.c.in b/version.c.in
index 1166419a..718df784 100644
--- a/version.c.in
+++ b/version.c.in
@@ -6,8 +6,5 @@ char markdown_version[] = VERSION
 #endif
 #if USE_AMALLOC
 		" DEBUG"
-#endif
-#if WITH_GITHUB_TAGS
-		" GITHUB-TAGS"
 #endif
 		;