diff --git a/msdos/src/bus/int_f5.c b/msdos/src/bus/int_f5.c
index d8e78a1..1dae0ff 100644
--- a/msdos/src/bus/int_f5.c
+++ b/msdos/src/bus/int_f5.c
@@ -12,18 +12,21 @@
  */
 
 #include <dos.h>
+#include <string.h>
 
 unsigned char int_f5(unsigned char dev, unsigned char command, unsigned char aux1, unsigned char aux2)
 {
     union REGS r;
-    
+
+    memset(&r,0,sizeof(union REGS));
+
     r.h.dl = 0x00;
     r.h.al = dev;
     r.h.ah = command;
     r.h.cl = aux1;
     r.h.ch = aux2;
     r.x.si = 0x00;
-    
+
     int86(0xF5,&r,&r);
 
     return r.h.al;
diff --git a/msdos/src/bus/int_f5_read.c b/msdos/src/bus/int_f5_read.c
index 109ea8e..da49a29 100644
--- a/msdos/src/bus/int_f5_read.c
+++ b/msdos/src/bus/int_f5_read.c
@@ -14,19 +14,23 @@
  */
 
 #include <dos.h>
+#include <string.h>
 
 unsigned char int_f5_read(unsigned char dev, unsigned char command, unsigned char aux1, unsigned char aux2, void *buf, unsigned short len)
 {
     union REGS r;
     struct SREGS sr;
 
+    memset(&r,0,sizeof(union REGS));
+    memset(&sr,0,sizeof(struct SREGS));
+
     r.h.dl = 0x40;
     r.h.al = dev;
     r.h.ah = command;
     r.h.cl = aux1;
     r.h.ch = aux2;
     r.x.si = 0x00;
-    
+
     sr.es  = FP_SEG(buf);
     r.x.bx = FP_OFF(buf);
     r.x.di = len;
diff --git a/msdos/src/bus/int_f5_write.c b/msdos/src/bus/int_f5_write.c
index 306ade3..7ae28d9 100644
--- a/msdos/src/bus/int_f5_write.c
+++ b/msdos/src/bus/int_f5_write.c
@@ -14,19 +14,23 @@
  */
 
 #include <dos.h>
+#include <string.h>
 
 unsigned char int_f5_write(unsigned char dev, unsigned char command, unsigned char aux1, unsigned char aux2, void *buf, unsigned short len)
 {
     union REGS r;
     struct SREGS sr;
 
+    memset(&r,0,sizeof(union REGS));
+    memset(&sr,0,sizeof(struct SREGS));
+
     r.h.dl = 0x80;
     r.h.al = dev;
     r.h.ah = command;
     r.h.cl = aux1;
     r.h.ch = aux2;
     r.x.si = 0x00;
-    
+
     sr.es  = FP_SEG(buf);
     r.x.bx = FP_OFF(buf);
     r.x.di = len;
diff --git a/msdos/src/fn_network/network_status.c b/msdos/src/fn_network/network_status.c
index aba0841..3ddda46 100644
--- a/msdos/src/fn_network/network_status.c
+++ b/msdos/src/fn_network/network_status.c
@@ -2,6 +2,7 @@
 #include <stdint.h>
 #include <fujinet-network.h>
 #include <fujinet-fuji-msdos.h>
+#include <string.h>
 
 uint8_t network_status(const char *devicespec, uint16_t *bw, uint8_t *c, uint8_t *err)
 {
@@ -14,6 +15,8 @@ uint8_t network_status(const char *devicespec, uint16_t *bw, uint8_t *c, uint8_t
     uint8_t err;
   } sr;
 
+  memset(&sr,0,sizeof(sr));
+
   ret = int_f5_read(device,'S',0x00,0x00,&sr,sizeof(sr));
 
   if (bw)
@@ -22,6 +25,6 @@ uint8_t network_status(const char *devicespec, uint16_t *bw, uint8_t *c, uint8_t
     *c = sr.c;
   if (err)
     *err = sr.err;
-  
-  return ret;
+
+  return ret == 'C' ? FN_ERR_OK : FN_ERR_IO_ERROR;
 }