diff --git a/include/villas/nodes/shmem.h b/include/villas/nodes/shmem.h
index 5648b706f..e4c5dbfe9 100644
--- a/include/villas/nodes/shmem.h
+++ b/include/villas/nodes/shmem.h
@@ -26,7 +26,7 @@ struct shmem {
 	int insize, outsize;		/**< Size of ingoing and outgoing queue, respectively. */
 	int cond_out;			/**< Whether to use a pthread_cond_t to signal if new samples are written to outqueue. */
 	int cond_in;			/**< Whether to use a pthread_cond_t to signal if new samples are written to inqueue. */
-	const char * const exec;	/**< External program to execute on start. */
+	char **exec;			/**< External program to execute on start. */
 
 	struct memtype *manager;	/**< Manager for the shared memory region. */
 	int fd;				/**< Handle as returned by shm_open().*/
diff --git a/include/villas/utils.h b/include/villas/utils.h
index 72a5efbd6..b9a6cd9bc 100644
--- a/include/villas/utils.h
+++ b/include/villas/utils.h
@@ -230,4 +230,4 @@ void rdtsc_sleep(uint64_t nanosecs, uint64_t start);
 /** Register a exit callback for program termination (SIGINT / SIGKILL). */
 void signals_init(void (*cb)(int signal, siginfo_t *sinfo, void *ctx));
 
-pid_t spawn(const char* name, char **argv);
+pid_t spawn(const char* name, char *const argv[]);
diff --git a/lib/nodes/shmem.c b/lib/nodes/shmem.c
index b78cebd68..c7b8b71c8 100644
--- a/lib/nodes/shmem.c
+++ b/lib/nodes/shmem.c
@@ -46,9 +46,11 @@ int shmem_parse(struct node *n, config_setting_t *cfg)
 
 		int i;
 		for (i = 0; i < config_setting_length(exec_cfg); i++) {
-			shm->exec[i] = config_setting_get_string_elem(exec_cfg, i);
-			if (!shm->exec[i])
+			const char *elm = config_setting_get_string_elem(exec_cfg, i);
+			if (!elm)
 				cerror(exec_cfg, "Invalid format for exec");
+			
+			shm->exec[i] = strdup(elm);
 		}
 
 		shm->exec[i] = NULL;
diff --git a/lib/utils.c b/lib/utils.c
index 2a9025990..a45c32558 100644
--- a/lib/utils.c
+++ b/lib/utils.c
@@ -302,15 +302,15 @@ void signals_init(void (*cb)(int signal, siginfo_t *sinfo, void *ctx))
 	sigaction(SIGCHLD, &sa_chld, NULL);
 }
 
-pid_t
-spawn(const char* name, char **argv) {
-	pid_t pid = fork();
-	switch(pid) {
-	case -1:
-		return -1;
-	case 0:
-		return execvp(name, argv);
-	default:
-		return pid;
+pid_t spawn(const char* name, char *const argv[])
+{
+	pid_t pid;
+	
+	pid = fork();
+	switch (pid) {
+		case -1: return -1;
+		case 0:  return execvp(name, (char * const*) argv);
 	}
+	
+	return pid;
 }