diff --git a/src/network/net_3c501.c b/src/network/net_3c501.c
index b3a903c7b..5b9fc0cac 100644
--- a/src/network/net_3c501.c
+++ b/src/network/net_3c501.c
@@ -373,7 +373,7 @@ elnkR3HardReset(threec501_t *dev)
 static __inline int
 padr_match(threec501_t *dev, const uint8_t *buf)
 {
-    const struct ether_header *hdr = (struct ether_header *) buf;
+    const struct ether_header *hdr = (const struct ether_header *) buf;
     int                        result;
 
     /* Checks own + broadcast as well as own + multicast. */
@@ -389,7 +389,7 @@ static __inline int
 padr_bcast(threec501_t *dev, const uint8_t *buf)
 {
     static uint8_t             aBCAST[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
-    const struct ether_header *hdr       = (struct ether_header *) buf;
+    const struct ether_header *hdr       = (const struct ether_header *) buf;
     int                        result    = (dev->RcvCmd.adr_match == EL_ADRM_BCAST) && !memcmp(hdr->ether_dhost, aBCAST, 6);
 
     return result;
@@ -401,8 +401,8 @@ padr_bcast(threec501_t *dev, const uint8_t *buf)
 static __inline int
 padr_mcast(threec501_t *dev, const uint8_t *buf)
 {
-    struct ether_header *hdr    = (struct ether_header *) buf;
-    int                  result = (dev->RcvCmd.adr_match == EL_ADRM_MCAST) && ETHER_IS_MULTICAST(hdr->ether_dhost);
+    const struct ether_header *hdr    = (const struct ether_header *) buf;
+    int                        result = (dev->RcvCmd.adr_match == EL_ADRM_MCAST) && ETHER_IS_MULTICAST(hdr->ether_dhost);
 
     return result;
 }
diff --git a/src/network/net_dp8390.c b/src/network/net_dp8390.c
index 1e50ddd45..1c308e913 100644
--- a/src/network/net_dp8390.c
+++ b/src/network/net_dp8390.c
@@ -66,7 +66,7 @@ mcast_index(const void *dst)
     uint32_t       crc = 0xffffffffL;
     int            carry;
     uint8_t        b;
-    const uint8_t *ep = (uint8_t *) dst;
+    const uint8_t *ep = (const uint8_t *) dst;
 
     for (int8_t i = 6; --i >= 0;) {
         b = *ep++;
diff --git a/src/network/net_ne2000.c b/src/network/net_ne2000.c
index 56f7facff..c7fba404f 100644
--- a/src/network/net_ne2000.c
+++ b/src/network/net_ne2000.c
@@ -812,7 +812,7 @@ static void
 nic_rom_init(nic_t *dev, char *s)
 {
     uint32_t temp;
-    FILE    *f;
+    FILE    *fp;
 
     if (s == NULL)
         return;
@@ -820,10 +820,10 @@ nic_rom_init(nic_t *dev, char *s)
     if (dev->bios_addr == 0)
         return;
 
-    if ((f = rom_fopen(s, "rb")) != NULL) {
-        fseek(f, 0L, SEEK_END);
-        temp = ftell(f);
-        fclose(f);
+    if ((fp = rom_fopen(s, "rb")) != NULL) {
+        fseek(fp, 0L, SEEK_END);
+        temp = ftell(fp);
+        fclose(fp);
         dev->bios_size = 0x10000;
         if (temp <= 0x8000)
             dev->bios_size = 0x8000;
diff --git a/src/network/net_pcnet.c b/src/network/net_pcnet.c
index 7cbe10e31..ab761acf3 100644
--- a/src/network/net_pcnet.c
+++ b/src/network/net_pcnet.c
@@ -47,6 +47,7 @@
 #include <86box/network.h>
 #include <86box/net_pcnet.h>
 #include <86box/bswap.h>
+#include <86box/plat_fallthrough.h>
 #include <86box/plat_unused.h>
 
 /* PCI info. */
@@ -748,7 +749,7 @@ static const uint32_t crctab[256] =
 static __inline int
 padr_match(nic_t *dev, const uint8_t *buf, UNUSED(int size))
 {
-    const struct ether_header *hdr = (struct ether_header *) buf;
+    const struct ether_header *hdr = (const struct ether_header *) buf;
     int                        result;
     uint8_t                    padr[6];
 
@@ -774,7 +775,7 @@ static __inline int
 padr_bcast(nic_t *dev, const uint8_t *buf, UNUSED(size_t size))
 {
     static uint8_t             aBCAST[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
-    const struct ether_header *hdr       = (struct ether_header *) buf;
+    const struct ether_header *hdr       = (const struct ether_header *) buf;
     int                        result    = !CSR_DRCVBC(dev) && !memcmp(hdr->ether_dhost, aBCAST, 6);
 
     pcnet_log(3, "%s: padr_bcast result=%d\n", dev->name, result);
@@ -785,7 +786,7 @@ padr_bcast(nic_t *dev, const uint8_t *buf, UNUSED(size_t size))
 static int
 ladr_match(nic_t *dev, const uint8_t *buf, UNUSED(size_t size))
 {
-    const struct ether_header *hdr = (struct ether_header *) buf;
+    const struct ether_header *hdr = (const struct ether_header *) buf;
 
     if ((hdr->ether_dhost[0] & 0x01) && ((uint64_t *) &dev->aCSR[8])[0] != 0LL) {
         int     index;
@@ -1998,7 +1999,7 @@ pcnet_bcr_writew(nic_t *dev, uint16_t rap, uint16_t val)
                     break;
             }
             dev->aCSR[58] = val;
-            /* fall through */
+            fallthrough;
         case BCR_LNKST:
         case BCR_LED1:
         case BCR_LED2:
diff --git a/src/network/network.c b/src/network/network.c
index eec85fcb0..4335c75f3 100644
--- a/src/network/network.c
+++ b/src/network/network.c
@@ -717,7 +717,7 @@ network_card_has_config(int card)
 }
 
 /* UI */
-char *
+const char *
 network_card_get_internal_name(int card)
 {
     return device_get_internal_name(net_cards[card]);
@@ -730,7 +730,7 @@ network_card_get_from_internal_name(char *s)
     int c = 0;
 
     while (net_cards[c] != NULL) {
-        if (!strcmp((char *) net_cards[c]->internal_name, s))
+        if (!strcmp(net_cards[c]->internal_name, s))
             return c;
         c++;
     }