diff --git a/VAX/vax610_sysdev.c b/VAX/vax610_sysdev.c
index f7417ef1..eb40e8d3 100644
--- a/VAX/vax610_sysdev.c
+++ b/VAX/vax610_sysdev.c
@@ -371,7 +371,7 @@ if (r != SCPE_OK) {                                     /* error? */
         }
     return r;
     }
-strncpy (cpu_boot_cmd, ptr, CBUFSIZE);                  /* save for reboot */
+strncpy (cpu_boot_cmd, ptr, CBUFSIZE-1);                /* save for reboot */
 return run_cmd (flag, "CPU");
 }
 
diff --git a/VAX/vax730_sys.c b/VAX/vax730_sys.c
index b8ce8b6f..d3575d95 100644
--- a/VAX/vax730_sys.c
+++ b/VAX/vax730_sys.c
@@ -478,7 +478,7 @@ if (r != SCPE_OK) {                                     /* error? */
         }
     return r;
     }
-strncpy (cpu_boot_cmd, ptr, CBUFSIZE);                  /* save for reboot */
+strncpy (cpu_boot_cmd, ptr, CBUFSIZE-1);                /* save for reboot */
 return run_cmd (flag, "CPU");
 }
 
diff --git a/VAX/vax750_cmi.c b/VAX/vax750_cmi.c
index b547730d..7c9d27d5 100644
--- a/VAX/vax750_cmi.c
+++ b/VAX/vax750_cmi.c
@@ -617,7 +617,7 @@ if (r != SCPE_OK) {                                     /* error? */
         }
     return r;
     }
-strncpy (cpu_boot_cmd, ptr, CBUFSIZE);                  /* save for reboot */
+strncpy (cpu_boot_cmd, ptr, CBUFSIZE-1);                /* save for reboot */
 return run_cmd (flag, "CPU");
 }
 
diff --git a/VAX/vax780_sbi.c b/VAX/vax780_sbi.c
index 339a8a02..f5d3e6a5 100644
--- a/VAX/vax780_sbi.c
+++ b/VAX/vax780_sbi.c
@@ -630,7 +630,7 @@ if (r != SCPE_OK) {                                     /* error? */
         }
     return r;
     }
-strncpy (cpu_boot_cmd, ptr, CBUFSIZE);                  /* save for reboot */
+strncpy (cpu_boot_cmd, ptr, CBUFSIZE-1);                /* save for reboot */
 return run_cmd (flag, "CPU");
 }
 
diff --git a/VAX/vax860_abus.c b/VAX/vax860_abus.c
index af7519de..735d3601 100644
--- a/VAX/vax860_abus.c
+++ b/VAX/vax860_abus.c
@@ -693,7 +693,7 @@ if (r != SCPE_OK) {                                     /* error? */
         }
     return r;
     }
-strncpy (cpu_boot_cmd, ptr, CBUFSIZE);                  /* save for reboot */
+strncpy (cpu_boot_cmd, ptr, CBUFSIZE-1);                /* save for reboot */
 return run_cmd (flag, "CPU");
 }