diff --git a/samples/cellular/modem_shell/overlay-esp-wifi.conf b/samples/cellular/modem_shell/overlay-esp-wifi.conf
index 06b351f2f95e..67bda4b0c70f 100644
--- a/samples/cellular/modem_shell/overlay-esp-wifi.conf
+++ b/samples/cellular/modem_shell/overlay-esp-wifi.conf
@@ -15,6 +15,8 @@ CONFIG_NET_IPV6=y
 CONFIG_NET_NATIVE=y
 
 CONFIG_NET_SHELL=y
+# Wi-Fi subsystem uses Zephyr's getopt.
+CONFIG_GETOPT_LIB=n
 CONFIG_NET_L2_WIFI_SHELL=y
 # Should be set when CONFIG_NET_L2_WIFI_SHELL is enabled.
 # Printing 'wifi scan' command results puts pressure on queues in new locking design in net_mgmt.
diff --git a/samples/cellular/modem_shell/overlay-nrf7002ek-wifi-scan-only.conf b/samples/cellular/modem_shell/overlay-nrf7002ek-wifi-scan-only.conf
index 73cf09e5ddc0..e8b67b207d3a 100644
--- a/samples/cellular/modem_shell/overlay-nrf7002ek-wifi-scan-only.conf
+++ b/samples/cellular/modem_shell/overlay-nrf7002ek-wifi-scan-only.conf
@@ -30,6 +30,8 @@ CONFIG_WIFI_NRF700X=y
 # Also see comments for CONFIG_HEAP_MEM_POOL_SIZE.
 CONFIG_WIFI_MGMT_SCAN_MAX_BSS_CNT=50
 
+# Wi-Fi subsystem uses Zephyr's getopt.
+CONFIG_GETOPT_LIB=n
 CONFIG_NET_L2_WIFI_SHELL=y
 # Should be set when CONFIG_NET_L2_WIFI_SHELL is enabled.
 # Printing 'wifi scan' command results puts pressure on queues in new locking design in net_mgmt.
diff --git a/samples/cellular/modem_shell/src/location/location_shell.c b/samples/cellular/modem_shell/src/location/location_shell.c
index 93013bea591e..e55eb2d0e547 100644
--- a/samples/cellular/modem_shell/src/location/location_shell.c
+++ b/samples/cellular/modem_shell/src/location/location_shell.c
@@ -9,6 +9,9 @@
 #include <string.h>
 
 #include <zephyr/shell/shell.h>
+#ifdef CONFIG_GETOPT
+#include <zephyr/posix/unistd.h>
+#endif
 #include <getopt.h>
 #include <net/nrf_cloud.h>
 #if defined(CONFIG_NRF_CLOUD_REST)
diff --git a/samples/cellular/modem_shell/src/ping/icmp_ping_shell.c b/samples/cellular/modem_shell/src/ping/icmp_ping_shell.c
index 9198fd888cfc..ca1ce9bdd7d3 100644
--- a/samples/cellular/modem_shell/src/ping/icmp_ping_shell.c
+++ b/samples/cellular/modem_shell/src/ping/icmp_ping_shell.c
@@ -8,6 +8,9 @@
 #include <zephyr/kernel.h>
 
 #include <zephyr/shell/shell.h>
+#ifdef CONFIG_GETOPT
+#include <zephyr/posix/unistd.h>
+#endif
 #include <getopt.h>
 
 #include "link_api.h"
diff --git a/samples/cellular/modem_shell/src/rest/rest_shell.c b/samples/cellular/modem_shell/src/rest/rest_shell.c
index def040e1523e..6b3fd4846d98 100644
--- a/samples/cellular/modem_shell/src/rest/rest_shell.c
+++ b/samples/cellular/modem_shell/src/rest/rest_shell.c
@@ -9,6 +9,9 @@
 #include <assert.h>
 
 #include <zephyr/shell/shell.h>
+#ifdef CONFIG_GETOPT
+#include <zephyr/posix/unistd.h>
+#endif
 #include <getopt.h>
 
 #include <zephyr/net/http/parser.h>
diff --git a/samples/cellular/modem_shell/src/sms/sms_shell.c b/samples/cellular/modem_shell/src/sms/sms_shell.c
index 194b76ad23c1..ab459a094b6d 100644
--- a/samples/cellular/modem_shell/src/sms/sms_shell.c
+++ b/samples/cellular/modem_shell/src/sms/sms_shell.c
@@ -8,6 +8,9 @@
 #include <assert.h>
 #include <string.h>
 #include <stdio.h>
+#ifdef CONFIG_GETOPT
+#include <zephyr/posix/unistd.h>
+#endif
 #include <getopt.h>
 
 #include "sms.h"