diff --git a/src/shell.cc b/src/shell.cc
index 24720cd..57f16f4 100644
--- a/src/shell.cc
+++ b/src/shell.cc
@@ -26,6 +26,39 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
+// Posix says that this variable just exists.
+// (On some systems this is also declared in unistd.h)
+extern char **environ;
+
+// Not the result borrows memory from env and thus it's lifetime.
+vector<const char*> prepareEnv(vector<string>& envs)
+{
+    map<string, const char*> env_map;
+    int i;
+
+    for (i = 0; environ[i]; i++) {
+        string e = environ[i];
+        vector<string> parts = splitString(e, '=');
+        env_map[parts[0]] = environ[i];
+    }
+
+    for (auto &e : envs) {
+        vector<string> parts = splitString(e, '=');
+        env_map[parts[0]] = e.c_str();
+        debug("(shell) env \"%s\"\n", e.c_str());
+    }
+
+    vector<const char*> env(env_map.size()+1);
+    i = 0;
+    for (auto &e : env_map) {
+        env[i] = e.second;
+        i++;
+    }
+    env[i] = NULL;
+
+    return env;
+}
+
 void invokeShell(string program, vector<string> args, vector<string> envs)
 {
     vector<const char*> argv(args.size()+2);
@@ -41,15 +74,7 @@ void invokeShell(string program, vector<string> args, vector<string> envs)
     }
     argv[i] = NULL;
 
-    vector<const char*> env(envs.size()+1);
-    env[0] = p;
-    i = 0;
-    for (auto &e : envs) {
-        env[i] = e.c_str();
-        i++;
-        debug("(shell) env \"%s\"\n", e.c_str());
-    }
-    env[i] = NULL;
+    vector<const char*> env = prepareEnv(envs);
 
     pid_t pid = fork();
     int status;
@@ -99,15 +124,7 @@ bool invokeBackgroundShell(string program, vector<string> args, vector<string> e
     }
     argv[i] = NULL;
 
-    vector<const char*> env(envs.size()+1);
-    env[0] = p;
-    i = 0;
-    for (auto &e : envs) {
-        env[i] = e.c_str();
-        i++;
-        debug("(bgshell) env \"%s\"\n", e.c_str());
-    }
-    env[i] = NULL;
+    vector<const char*> env = prepareEnv(envs);
 
     if (pipe(link) == -1) {
         error("(bgshell) could not create pipe!\n");
@@ -241,15 +258,7 @@ int invokeShellCaptureOutput(string program, vector<string> args, vector<string>
     }
     argv[i] = NULL;
 
-    vector<const char*> env(envs.size()+1);
-    env[0] = p;
-    i = 0;
-    for (auto &e : envs) {
-        env[i] = e.c_str();
-        i++;
-        debug("(shell) env \"%s\"\n", e.c_str());
-    }
-    env[i] = NULL;
+    vector<const char*> env = prepareEnv(envs);
 
     if (pipe(link) == -1) {
         error("(shell) could not create pipe!\n");
diff --git a/test.sh b/test.sh
index 25e4409..9368a53 100755
--- a/test.sh
+++ b/test.sh
@@ -57,6 +57,9 @@ if [ "$?" != "0" ]; then RC="1"; fi
 tests/test_shell2.sh $PROG
 if [ "$?" != "0" ]; then RC="1"; fi
 
+tests/test_shell_env.sh $PROG
+if [ "$?" != "0" ]; then RC="1"; fi
+
 tests/test_meterfiles.sh $PROG
 if [ "$?" != "0" ]; then RC="1"; fi
 
diff --git a/tests/test_shell_env.sh b/tests/test_shell_env.sh
new file mode 100755
index 0000000..7e20824
--- /dev/null
+++ b/tests/test_shell_env.sh
@@ -0,0 +1,29 @@
+#!/bin/sh
+
+PROG="$1"
+
+mkdir -p testoutput
+TEST=testoutput
+
+TESTNAME="Test shell environment"
+TESTRESULT="ERROR"
+
+export MY_ENV_TEST="hello world"
+
+$PROG --shell='echo MY_ENV_TEST="$MY_ENV_TEST"' simulations/simulation_shell.txt MWW supercom587 12345678 "" > $TEST/test_output.txt 2> $TEST/test_stderr.txt
+if [ "$?" = "0" ]
+then
+    echo 'MY_ENV_TEST=hello world' > $TEST/test_expected.txt
+    diff $TEST/test_expected.txt $TEST/test_output.txt
+    if [ "$?" = "0" ]
+    then
+        echo OK: $TESTNAME
+        TESTRESULT="OK"
+    fi
+fi
+
+if [ "$TESTRESULT" = "ERROR" ]
+then
+    echo ERROR: $TESTNAME
+    exit 1
+fi