diff --git a/arch/sandbox/cpu/os.c b/arch/sandbox/cpu/os.c
index d23aad3..f5000e6 100644
--- a/arch/sandbox/cpu/os.c
+++ b/arch/sandbox/cpu/os.c
@@ -153,7 +153,7 @@
 		printf("Cannot seek to start of file '%s'\n", fname);
 		goto err;
 	}
-	*bufp = malloc(size);
+	*bufp = os_malloc(size);
 	if (!*bufp) {
 		printf("Not enough memory to read file '%s'\n", fname);
 		ret = -ENOMEM;
@@ -391,8 +391,8 @@
 	state->argv = argv;
 
 	/* dynamically construct the arguments to the system getopt_long */
-	short_opts = malloc(sizeof(*short_opts) * num_options * 2 + 1);
-	long_opts = malloc(sizeof(*long_opts) * (num_options + 1));
+	short_opts = os_malloc(sizeof(*short_opts) * num_options * 2 + 1);
+	long_opts = os_malloc(sizeof(*long_opts) * (num_options + 1));
 	if (!short_opts || !long_opts)
 		return 1;
 
@@ -471,7 +471,7 @@
 
 	while (node) {
 		next = node->next;
-		free(node);
+		os_free(node);
 		node = next;
 	}
 }
@@ -496,7 +496,7 @@
 	/* Create a buffer upfront, with typically sufficient size */
 	dirlen = strlen(dirname) + 2;
 	len = dirlen + 256;
-	fname = malloc(len);
+	fname = os_malloc(len);
 	if (!fname) {
 		ret = -ENOMEM;
 		goto done;
@@ -509,7 +509,7 @@
 			ret = errno;
 			break;
 		}
-		next = malloc(sizeof(*node) + strlen(entry->d_name) + 1);
+		next = os_malloc(sizeof(*node) + strlen(entry->d_name) + 1);
 		if (!next) {
 			os_dirent_free(head);
 			ret = -ENOMEM;
@@ -518,10 +518,10 @@
 		if (dirlen + strlen(entry->d_name) > len) {
 			len = dirlen + strlen(entry->d_name);
 			old_fname = fname;
-			fname = realloc(fname, len);
+			fname = os_realloc(fname, len);
 			if (!fname) {
-				free(old_fname);
-				free(next);
+				os_free(old_fname);
+				os_free(next);
 				os_dirent_free(head);
 				ret = -ENOMEM;
 				goto done;
@@ -555,7 +555,7 @@
 
 done:
 	closedir(dir);
-	free(fname);
+	os_free(fname);
 	return ret;
 }
 
@@ -672,7 +672,7 @@
 	for (argc = 0; (*argvp)[argc]; argc++)
 		;
 
-	argv = malloc((argc + count + 1) * sizeof(char *));
+	argv = os_malloc((argc + count + 1) * sizeof(char *));
 	if (!argv) {
 		printf("Out of memory for %d argv\n", count);
 		return -ENOMEM;
@@ -755,7 +755,7 @@
 		os_exit(2);
 
 	err = execv(fname, argv);
-	free(argv);
+	os_free(argv);
 	if (err) {
 		perror("Unable to run image");
 		printf("Image filename '%s'\n", fname);
diff --git a/arch/sandbox/cpu/spl.c b/arch/sandbox/cpu/spl.c
index e7b4b50..6926e24 100644
--- a/arch/sandbox/cpu/spl.c
+++ b/arch/sandbox/cpu/spl.c
@@ -43,10 +43,14 @@
 		return ret;
 	}
 
-	/* Set up spl_image to boot from jump_to_image_no_args() */
-	spl_image->arg = strdup(fname);
+	/*
+	 * Set up spl_image to boot from jump_to_image_no_args(). Allocate this
+	 * outsdide the RAM buffer (i.e. don't use strdup()).
+	 */
+	spl_image->arg = os_malloc(strlen(fname) + 1);
 	if (!spl_image->arg)
-		return log_msg_ret("Setup exec filename", -ENOMEM);
+		return log_msg_ret("exec", -ENOMEM);
+	strcpy(spl_image->arg, fname);
 
 	return 0;
 }
diff --git a/arch/sandbox/cpu/start.c b/arch/sandbox/cpu/start.c
index 483a264..c4c4128 100644
--- a/arch/sandbox/cpu/start.c
+++ b/arch/sandbox/cpu/start.c
@@ -88,7 +88,7 @@
 
 	/* Sort the options */
 	size = sizeof(*sorted_opt) * num_options;
-	sorted_opt = malloc(size);
+	sorted_opt = os_malloc(size);
 	if (!sorted_opt) {
 		printf("No memory to sort options\n");
 		os_exit(1);
@@ -188,7 +188,7 @@
 	int len;
 
 	len = strlen(state->argv[0]) + strlen(fmt) + 1;
-	fname = malloc(len);
+	fname = os_malloc(len);
 	if (!fname)
 		return -ENOMEM;
 	snprintf(fname, len, fmt, state->argv[0]);
@@ -208,7 +208,7 @@
 	int len;
 
 	len = strlen(state->argv[0]) + strlen(fmt) + 1;
-	fname = malloc(len);
+	fname = os_malloc(len);
 	if (!fname)
 		return -ENOMEM;
 	strcpy(fname, state->argv[0]);
@@ -436,16 +436,18 @@
 {
 	struct sandbox_state *state;
 	gd_t data;
+	int size;
 	int ret;
 
 	/*
 	 * Copy argv[] so that we can pass the arguments in the original
 	 * sequence when resetting the sandbox.
 	 */
-	os_argv = calloc(argc + 1, sizeof(char *));
+	size = sizeof(char *) * (argc + 1);
+	os_argv = os_malloc(size);
 	if (!os_argv)
 		os_exit(1);
-	memcpy(os_argv, argv, sizeof(char *) * (argc + 1));
+	memcpy(os_argv, argv, size);
 
 	memset(&data, '\0', sizeof(data));
 	gd = &data;
diff --git a/arch/sandbox/cpu/state.c b/arch/sandbox/cpu/state.c
index b2901b7..4ffaf16 100644
--- a/arch/sandbox/cpu/state.c
+++ b/arch/sandbox/cpu/state.c
@@ -29,17 +29,17 @@
 		return 0;
 
 	size = used + extra_size;
-	buf = malloc(size);
+	buf = os_malloc(size);
 	if (!buf)
 		return -ENOMEM;
 
 	ret = fdt_open_into(blob, buf, size);
 	if (ret) {
-		free(buf);
+		os_free(buf);
 		return -EIO;
 	}
 
-	free(blob);
+	os_free(blob);
 	state->state_fdt = buf;
 	return 0;
 }
@@ -55,7 +55,7 @@
 		printf("Cannot find sandbox state file '%s'\n", fname);
 		return -ENOENT;
 	}
-	state->state_fdt = malloc(size);
+	state->state_fdt = os_malloc(size);
 	if (!state->state_fdt) {
 		puts("No memory to read sandbox state\n");
 		return -ENOMEM;
@@ -77,7 +77,7 @@
 err_read:
 	os_close(fd);
 err_open:
-	free(state->state_fdt);
+	os_free(state->state_fdt);
 	state->state_fdt = NULL;
 
 	return ret;
@@ -244,7 +244,7 @@
 	/* Create a state FDT if we don't have one */
 	if (!state->state_fdt) {
 		size = 0x4000;
-		state->state_fdt = malloc(size);
+		state->state_fdt = os_malloc(size);
 		if (!state->state_fdt) {
 			puts("No memory to create FDT\n");
 			return -ENOMEM;
@@ -302,7 +302,7 @@
 err_write:
 	os_close(fd);
 err_create:
-	free(state->state_fdt);
+	os_free(state->state_fdt);
 
 	return ret;
 }
@@ -419,8 +419,8 @@
 	if (state->jumped_fname)
 		os_unlink(state->jumped_fname);
 
-	if (state->state_fdt)
-		free(state->state_fdt);
+	os_free(state->state_fdt);
+	os_free(state->ram_buf);
 	memset(state, '\0', sizeof(*state));
 
 	return 0;