diff --git a/libc/include/regex.h b/libc/include/regex.h
index 8681a12d..dd0bfcca 100644
--- a/libc/include/regex.h
+++ b/libc/include/regex.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2015 Jonas 'Sortie' Termansen.
+ * Copyright (c) 2014, 2015, 2016 Jonas 'Sortie' Termansen.
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -140,6 +140,9 @@ typedef struct
 
 #define REG_NOTBOL (1 << 0)
 #define REG_NOTEOL (1 << 1)
+#if __USE_SORTIX
+#define REG_STARTEND (1 << 2)
+#endif
 
 #define REG_NOMATCH 1
 #define REG_BADPAT 2
@@ -154,6 +157,9 @@ typedef struct
 #define REG_ERANGE 11
 #define REG_ESPACE 12
 #define REG_BADRPT 13
+#if __USE_SORTIX
+#define REG_INVARG 14
+#endif
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/libc/regex/regerror.c b/libc/regex/regerror.c
index aa054193..b372537a 100644
--- a/libc/regex/regerror.c
+++ b/libc/regex/regerror.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2015 Jonas 'Sortie' Termansen.
+ * Copyright (c) 2014, 2015, 2016 Jonas 'Sortie' Termansen.
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -43,6 +43,7 @@ size_t regerror(int errnum,
 	case REG_ERANGE: msg = "Invalid endpoint in range expression"; break;
 	case REG_ESPACE: msg = "Out of memory"; break;
 	case REG_BADRPT: msg = "'?', '*', or '+' not preceded by valid regular expression"; break;
+	case REG_INVARG: msg = "Invalid arguments"; break;
 	}
 	if ( errbuf_size )
 		strlcpy(errbuf, msg, errbuf_size);
diff --git a/libc/regex/regexec.c b/libc/regex/regexec.c
index c60b5eac..6ab125ca 100644
--- a/libc/regex/regexec.c
+++ b/libc/regex/regexec.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2015 Jonas 'Sortie' Termansen.
+ * Copyright (c) 2014, 2015, 2016 Jonas 'Sortie' Termansen.
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -21,6 +21,7 @@
 #include <pthread.h>
 #include <regex.h>
 #include <stdbool.h>
+#include <string.h>
 
 #define QUEUE_CURRENT_STATE(new_state) \
 { \
@@ -105,6 +106,21 @@ int regexec(const regex_t* restrict regex_const,
 	if ( regex->re_cflags & REG_NOSUB )
 		nmatch = 0;
 
+	size_t start;
+	size_t end;
+	if ( eflags & REG_STARTEND )
+	{
+		if ( pmatch[0].rm_so < 0 || pmatch[0].rm_eo < pmatch[0].rm_so )
+			return REG_INVARG;
+		start = pmatch[0].rm_so;
+		end = pmatch[0].rm_eo;
+	}
+	else
+	{
+		start = 0;
+		end = strlen(string);
+	}
+
 	for ( size_t i = 0; i < nmatch; i++ )
 	{
 		pmatch[i].rm_so = -1;
@@ -123,7 +139,7 @@ int regexec(const regex_t* restrict regex_const,
 
 	regex->re->re_is_current = 0;
 
-	for ( size_t i = 0; true; i++ )
+	for ( size_t i = start; i <= end; i++ )
 	{
 		if ( !regex->re->re_is_current && result == REG_NOMATCH )
 		{
@@ -143,7 +159,7 @@ int regexec(const regex_t* restrict regex_const,
 				regex->re->re_matches[m].rm_eo = -1;
 			}
 		}
-		char c = string[i];
+		char c = i < end ? string[i] : '\0';
 		for ( struct re* state = current_states;
 		      state;
 		      state = state->re_current_state_next )
@@ -237,9 +253,6 @@ int regexec(const regex_t* restrict regex_const,
 
 		if ( current_states == NULL && result == 0 )
 			break;
-
-		if ( c == '\0' )
-			break;
 	}
 
 	pthread_mutex_unlock(&regex->re_lock);