diff --git a/LibC/stdlib.cpp b/LibC/stdlib.cpp
index cabcda573da..74d7d07939d 100644
--- a/LibC/stdlib.cpp
+++ b/LibC/stdlib.cpp
@@ -46,6 +46,16 @@ void abort()
     raise(SIGABRT);
 }
 
+static HashTable<char*> s_malloced_environment_variables;
+
+static void free_environment_variable_if_needed(const char* var)
+{
+    if (!s_malloced_environment_variables.contains((char*)var))
+        return;
+    free((void*)var);
+    s_malloced_environment_variables.remove((char*)var);
+}
+
 char* getenv(const char* name)
 {
     size_t vl = strlen(name);
@@ -89,9 +99,22 @@ int unsetenv(const char* name)
     // Shuffle the existing array down by one.
     memmove(&environ[skip], &environ[skip+1], ((environ_size-1)-skip) * sizeof(environ[0]));
     environ[environ_size-1] = nullptr;
+
+    free_environment_variable_if_needed(name);
     return 0;
 }
 
+int setenv(const char* name, const char* value, int overwrite)
+{
+    if (!overwrite && !getenv(name))
+        return 0;
+    auto length = strlen(name) + strlen(value) + 2;
+    auto* var = (char*)malloc(length);
+    snprintf(var, length, "%s=%s", name, value);
+    s_malloced_environment_variables.set(var);
+    return putenv(var);
+}
+
 int putenv(char* new_var)
 {
     char* new_eq = strchr(new_var, '=');
@@ -111,6 +134,7 @@ int putenv(char* new_var)
             continue; // can't match
 
         if (strncmp(new_var, old_var, new_var_len) == 0) {
+            free_environment_variable_if_needed(old_var);
             environ[environ_size] = new_var;
             return 0;
         }
diff --git a/LibC/stdlib.h b/LibC/stdlib.h
index 946a1d82748..a310ee5e11e 100644
--- a/LibC/stdlib.h
+++ b/LibC/stdlib.h
@@ -18,6 +18,7 @@ void* realloc(void* ptr, size_t);
 char* getenv(const char* name);
 int putenv(char*);
 int unsetenv(const char*);
+int setenv(const char* name, const char* value, int overwrite);
 int atoi(const char*);
 long atol(const char*);
 long long atoll(const char*);
diff --git a/Shell/main.cpp b/Shell/main.cpp
index b596fc2c931..47a2bc2ef92 100644
--- a/Shell/main.cpp
+++ b/Shell/main.cpp
@@ -72,13 +72,7 @@ static int sh_export(int argc, char** argv)
         return 1;
     }
 
-    // FIXME: Yes, this leaks.
-    // Maybe LibCore should grow a CEnvironment which is secretly a map to char*,
-    // so it can keep track of the environment pointers as needed?
-    const auto& s = String::format("%s=%s", parts[0].characters(), parts[1].characters());
-    char *ev = strndup(s.characters(), s.length());
-    putenv(ev);
-    return 0;
+    return setenv(parts[0].characters(), parts[1].characters(), 1);
 }
 
 static int sh_unset(int argc, char** argv)
@@ -494,9 +488,7 @@ int main(int argc, char** argv)
         if (pw) {
             g.username = pw->pw_name;
             g.home = pw->pw_dir;
-            const auto& s = String::format("HOME=%s", pw->pw_dir);
-            char *ev = strndup(s.characters(), s.length());
-            putenv(ev);
+            setenv("HOME", pw->pw_dir, 1);
         }
         endpwent();
     }