diff --git a/libmaxsi/Makefile b/libmaxsi/Makefile
index 72f8f3a2..528611cf 100644
--- a/libmaxsi/Makefile
+++ b/libmaxsi/Makefile
@@ -50,6 +50,7 @@ start.o \
 time.o \
 random.o \
 abs.o \
+env.o \
 integer.o \
 c++.o \
 memory.o \
diff --git a/libmaxsi/env.cpp b/libmaxsi/env.cpp
new file mode 100644
index 00000000..64444b9d
--- /dev/null
+++ b/libmaxsi/env.cpp
@@ -0,0 +1,192 @@
+/*******************************************************************************
+
+	COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2012.
+
+	This file is part of LibMaxsi.
+
+	LibMaxsi is free software: you can redistribute it and/or modify it under
+	the terms of the GNU Lesser General Public License as published by the Free
+	Software Foundation, either version 3 of the License, or (at your option)
+	any later version.
+
+	LibMaxsi is distributed in the hope that it will be useful, but WITHOUT ANY
+	WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+	FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
+	details.
+
+	You should have received a copy of the GNU Lesser General Public License
+	along with LibMaxsi. If not, see <http://www.gnu.org/licenses/>.
+
+	env.cpp
+	Environmental variables utilities.
+
+*******************************************************************************/
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+
+/* Since legacy applications rely on being able to modify the environ variable,
+   we have to keep track of whether it is what we expect and whether we know the
+   size of it. If it changed, we need to recount, as well as malloc a copy of it
+   if we wish to make changes. */
+extern "C" { char** environ = NULL; }
+static char** environ_malloced = NULL;
+static char** environ_counted = NULL;
+size_t environlen = 0;
+size_t environroom = 0;
+
+static inline bool environismalloced()
+{
+	return environ && environ == environ_malloced;
+}
+
+extern "C" const char* const* getenviron(void)
+{
+	return environ;
+}
+
+extern "C" size_t envlength(void)
+{
+	if ( !environ ) { return 0; }
+	if ( environ_counted != environ )
+	{
+		size_t count = 0;
+		while ( environ[count] ) { count++; }
+		environ_counted = environ;
+		environlen = count;
+	}
+	return environlen;
+}
+
+extern "C" const char* getenvindexed(size_t index)
+{
+	if ( envlength() <= index ) { errno = EBOUND; return NULL; }
+	return environ[index];
+}
+
+extern "C" const char* sortix_getenv(const char* name)
+{
+	size_t equalpos = strcspn(name, "=");
+	if ( name[equalpos] == '=' ) { return NULL; }
+	size_t namelen = equalpos;
+	size_t envlen = envlength();
+	for ( size_t i = 0; i < envlen; i++ )
+	{
+		if ( strncmp(name, environ[i], namelen) ) { continue; }
+		if ( environ[i][namelen] != '=' ) { continue; }
+		return environ[i] + namelen + 1;
+	}
+	return NULL;
+}
+
+extern "C" char* getenv(const char* name)
+{
+	return (char*) sortix_getenv(name);
+}
+
+static bool makeenvironmalloced()
+{
+	if ( environismalloced() ) { return true; }
+	size_t envlen = envlength();
+	size_t newenvlen = envlen;
+	size_t newenvsize = sizeof(char*) * (newenvlen+1);
+	char** newenviron = (char**) malloc(newenvsize);
+	if ( !newenviron ) { return false; }
+	size_t sofar = 0;
+	for ( size_t i = 0; i < envlen; i++ )
+	{
+		newenviron[i] = strdup(environ[i]);
+		if ( !newenviron[i] ) { goto cleanup; }
+		sofar = i;
+	}
+	newenviron[envlen] = NULL;
+	environlen = environroom = newenvlen;
+	environ = environ_malloced = environ_counted = newenviron;
+	return true;
+cleanup:
+	for ( size_t i = 0; i < sofar; i++ ) { free(newenviron[i]); }
+	free(newenviron);
+	return false;
+}
+
+extern "C" int clearenv(void)
+{
+	if ( !environ ) { return 0; }
+	if ( environismalloced() )
+	{
+		for ( char** varp = environ; *varp; varp++ ) { free(*varp); }
+		free(environ);
+	}
+	environ = environ_counted = environ_malloced = NULL;
+	return 0;
+}
+
+static bool doputenv(char* str, char* freeme, bool overwrite)
+{
+	if ( !makeenvironmalloced() ) { free(freeme); return false; }
+	size_t strvarnamelen = strcspn(str, "=");
+	for ( size_t i = 0; i < envlength(); i++ )
+	{
+		char* var = environ[i];
+		if ( strncmp(str, var, strvarnamelen) ) { continue; }
+		if ( !overwrite ) { free(freeme); return true; }
+		free(var);
+		environ[i] = str;
+		return true;
+	}
+	if ( environlen == environroom )
+	{
+		size_t newenvironroom = environroom ? 2 * environroom : 16;
+		size_t newenvironsize = sizeof(char*) * (newenvironroom+1);
+		char** newenviron = (char**) realloc(environ, newenvironsize);
+		if ( !newenviron ) { free(freeme); return false; }
+		environ = environ_malloced = environ_counted = newenviron;
+		environroom = newenvironroom;
+	}
+	environ[environlen++] = str;
+	environ[environlen] = NULL;
+	return true;
+}
+
+extern "C" int setenv(const char* name, const char* value, int overwrite)
+{
+	if ( !name || !name[0] || strchr(name, '=') ) { errno = EINVAL; return -1; }
+	char* str = (char*) malloc(strlen(name) + 1 + strlen(value) + 1);
+	if ( !str ) { return -1; }
+	stpcpy(stpcpy(stpcpy(str, name), "="), value);
+	if ( !doputenv(str, str, overwrite) ) { return -1; }
+	return 0;
+}
+
+extern "C" int putenv(char* str)
+{
+	if ( !strchr(str, '=') ) { errno = EINVAL; return -1; }
+	if ( !doputenv(str, NULL, true) ) { return -1; }
+	return 0;
+}
+
+extern "C" int unsetenv(const char* name)
+{
+	size_t equalpos = strcspn(name, "=");
+	if ( name[equalpos] == '=' ) { return 0; }
+	size_t namelen = equalpos;
+	size_t envlen = envlength();
+	for ( size_t i = 0; i < envlen; i++ )
+	{
+		if ( strncmp(name, environ[i], namelen) ) { continue; }
+		if ( environ[i][namelen] != '=' ) { continue; }
+		if ( environismalloced() )
+		{
+			char* str = environ[i];
+			free(str);
+		}
+		if ( i < envlen-1 ) { environ[i] = environ[envlen-1]; }
+		environ[--environlen] = NULL;
+		return 0;
+	}
+	return 0;
+}
+
diff --git a/libmaxsi/include/stdlib.h b/libmaxsi/include/stdlib.h
index f7faea4a..92cfb470 100644
--- a/libmaxsi/include/stdlib.h
+++ b/libmaxsi/include/stdlib.h
@@ -56,20 +56,39 @@ void* calloc(size_t, size_t);
 void exit(int);
 void _Exit(int status);
 void free(void*);
-char* getenv(const char*);
 long labs(long);
 long long llabs(long long);
 void* malloc(size_t);
 #if !defined(_SORTIX_SOURCE)
 char* mktemp(char* templ);
 #endif
+int putenv(char*);
 void qsort(void*, size_t, size_t, int (*)(const void*, const void*));
 int rand(void);
 void* realloc(void*, size_t);
+int setenv(const char*, const char*, int);
 long strtol(const char* restrict, char** restrict, int);
 unsigned long strtoul(const char* restrict, char** restrict, int);
 unsigned long long strtoull(const char* restrict, char** restrict, int);
 long long strtoll(const char* restrict, char** restrict, int);
+int unsetenv(const char*);
+
+#if defined(_SORTIX_SOURCE) || defined(_WANT_SORTIX_ENV)
+const char* const* getenviron(void);
+size_t envlength(void);
+const char* getenvindexed(size_t index);
+const char* sortix_getenv(const char* name);
+#endif
+#if (defined(_SOURCE_SOURCE) && __SORTIX_STDLIB_REDIRECTS) || \
+    defined(_WANT_SORTIX_ENV)
+const char* getenv(const char* name) asm ("sortix_getenv");
+#else
+char* getenv(const char*);
+#endif
+#if defined(_SORTIX_SOURCE) || defined(_SVID_SOURCE) || defined(_XOPEN_SOURCE) \
+    || defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+int clearenv(void);
+#endif
 
 /* TODO: These are not implemented in libmaxsi/sortix yet. */
 #if defined(__SORTIX_SHOW_UNIMPLEMENTED)
@@ -99,11 +118,9 @@ long nrand48(unsigned short[3]);
 int posix_memalign(void**, size_t, size_t);
 int posix_openpt(int);
 char* ptsname(int);
-int putenv(char*);
 long random(void);
 char* realpath(const char* restrict, char* restrict);
 unsigned short *seed48(unsigned short [3]);
-int setenv(const char*, const char*, int);
 void setkey(const char*);
 char* setstate(char*);
 void srand(unsigned);
@@ -114,7 +131,6 @@ float strtof(const char* restrict, char** restrict);
 long double strtold(const char* restrict, char** restrict);
 int system(const char*);
 int unlockpt(int);
-int unsetenv(const char*);
 size_t wcstombs(char* restrict, const wchar_t *restrict, size_t);
 int wctomb(char*, wchar_t);
 
diff --git a/libmaxsi/process.cpp b/libmaxsi/process.cpp
index ab624d41..868ce177 100644
--- a/libmaxsi/process.cpp
+++ b/libmaxsi/process.cpp
@@ -40,8 +40,6 @@ namespace Maxsi
 		DEFN_SYSCALL0(pid_t, SysGetParentPID, SYSCALL_GETPPID);
 		DEFN_SYSCALL3(pid_t, SysWait, SYSCALL_WAIT, pid_t, int*, int);
 
-		extern "C" char** environ = NULL;
-
 		void Abort()
 		{
 			// TODO: Send SIGABRT instead!
@@ -102,11 +100,6 @@ namespace Maxsi
 		{
 			return waitpid(-1, status, 0);
 		}
-
-		extern "C" char* getenv(const char* name)
-		{
-			return NULL;
-		}
 	}
 }