diff --git a/kernel/syscall.c b/kernel/syscall.c
index 66ab98d9..d3c0f6f4 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -2146,11 +2146,9 @@ SYSCALL_DECLARE(execve)
 {
 	int error;
 	long ret;
-	char *empty_envp[1] = {NULL};
 	const char *filename = (const char *)ihk_mc_syscall_arg0(ctx);
 	char **argv = (char **)ihk_mc_syscall_arg1(ctx);
-	char **envp = (char **)ihk_mc_syscall_arg2(ctx) ? 
-		(char **)ihk_mc_syscall_arg2(ctx) : empty_envp;
+	char **envp = (char **)ihk_mc_syscall_arg2(ctx);
 
 	char *argv_flat = NULL;
 	int argv_flat_len = 0;
@@ -2210,7 +2208,7 @@ SYSCALL_DECLARE(execve)
 	/* Flatten argv and envp into kernel-space buffers */
 	argv_flat_len = flatten_strings_from_user(-1, (desc->shell_path[0] ? 
 				desc->shell_path : NULL), argv, &argv_flat);
-	if (argv_flat_len == 0) {
+	if (argv_flat_len < 0) {
 		char *kfilename;
 		int len = strlen_user(filename);
 
@@ -2220,12 +2218,12 @@ SYSCALL_DECLARE(execve)
 		kprintf("ERROR: no argv for executable: %s?\n", kfilename? kfilename: "");
 		if(kfilename)
 			kfree(kfilename);
-		ret = -EINVAL;
+		ret = argv_flat_len;
 		goto end;
 	}
 
 	envp_flat_len = flatten_strings_from_user(-1, NULL, envp, &envp_flat);
-	if (envp_flat_len == 0) {
+	if (envp_flat_len < 0) {
 		char *kfilename;
 		int len = strlen_user(filename);
 
@@ -2235,7 +2233,7 @@ SYSCALL_DECLARE(execve)
 		kprintf("ERROR: no envp for executable: %s?\n", kfilename? kfilename: "");
 		if(kfilename)
 			kfree(kfilename);
-		ret = -EINVAL;
+		ret = envp_flat_len;
 		goto end;
 	}
 
diff --git a/lib/string.c b/lib/string.c
index 8977747f..ab194e27 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -280,6 +280,18 @@ int flatten_strings_from_user(int nr_strings, char *first, char **strings, char
 	long r;
 	int n, ret;
 
+	/* When strings is NULL, make array one NULL */
+	if (!strings) {
+		full_len = sizeof(long) + sizeof(char *);
+		_flat = kmalloc(full_len, IHK_MC_AP_NOWAIT);
+		if (!_flat) {
+			return -ENOMEM;
+		}
+		memset(_flat, 0, full_len);
+		*flat = (char *)_flat;
+		return full_len;
+	}
+
 	/* How many strings do we have? */
 	if (nr_strings == -1) {
 		nr_strings = 0;