diff --git a/usr.bin/truss/amd64-fbsd.c b/usr.bin/truss/amd64-fbsd.c
index d0be3e6b141a..7ece9ca6d258 100644
--- a/usr.bin/truss/amd64-fbsd.c
+++ b/usr.bin/truss/amd64-fbsd.c
@@ -64,7 +64,7 @@ static const char rcsid[] =
 
 #include "syscalls.h"
 
-static int nsyscalls = sizeof(syscallnames) / sizeof(syscallnames[0]);
+static int nsyscalls = nitems(syscallnames);
 
 /*
  * This is what this particular file uses to keep track of a system call.
diff --git a/usr.bin/truss/amd64-fbsd32.c b/usr.bin/truss/amd64-fbsd32.c
index 74d45a2189d5..42a4e47c2b11 100644
--- a/usr.bin/truss/amd64-fbsd32.c
+++ b/usr.bin/truss/amd64-fbsd32.c
@@ -64,8 +64,7 @@ static const char rcsid[] =
 
 #include "freebsd32_syscalls.h"
 
-static int nsyscalls = sizeof(freebsd32_syscallnames) /
-    sizeof(freebsd32_syscallnames[0]);
+static int nsyscalls = nitems(freebsd32_syscallnames);
 
 /*
  * This is what this particular file uses to keep track of a system call.
diff --git a/usr.bin/truss/amd64-linux32.c b/usr.bin/truss/amd64-linux32.c
index 2c025a334629..be5029ed80b3 100644
--- a/usr.bin/truss/amd64-linux32.c
+++ b/usr.bin/truss/amd64-linux32.c
@@ -61,8 +61,7 @@ static const char rcsid[] =
 
 #include "linux32_syscalls.h"
 
-static int nsyscalls =
-	sizeof(linux32_syscallnames) / sizeof(linux32_syscallnames[0]);
+static int nsyscalls = nitems(linux32_syscallnames);
 
 /*
  * This is what this particular file uses to keep track of a system call.
@@ -310,8 +309,7 @@ amd64_linux32_syscall_exit(struct trussinfo *trussinfo,
 	 * but that complicates things considerably.
 	 */
 	if (errorp) {
-		for (i = 0;
-		    (size_t)i < sizeof(bsd_to_linux_errno) / sizeof(int); i++) {
+		for (i = 0; (size_t)i < nitems(bsd_to_linux_errno); i++) {
 			if (retval == bsd_to_linux_errno[i])
 				break;
 		}
diff --git a/usr.bin/truss/arm-fbsd.c b/usr.bin/truss/arm-fbsd.c
index dd1ae0896483..2fef59d8da65 100644
--- a/usr.bin/truss/arm-fbsd.c
+++ b/usr.bin/truss/arm-fbsd.c
@@ -64,7 +64,7 @@ __FBSDID("$FreeBSD$");
 #include "syscalls.h"
 
 
-static int nsyscalls = sizeof(syscallnames) / sizeof(syscallnames[0]);
+static int nsyscalls = nitems(syscallnames);
 
 /*
  * This is what this particular file uses to keep track of a system call.
diff --git a/usr.bin/truss/i386-fbsd.c b/usr.bin/truss/i386-fbsd.c
index 89879d2ff543..788d008b734d 100644
--- a/usr.bin/truss/i386-fbsd.c
+++ b/usr.bin/truss/i386-fbsd.c
@@ -64,7 +64,7 @@ static const char rcsid[] =
 
 #include "syscalls.h"
 
-static int nsyscalls = sizeof(syscallnames) / sizeof(syscallnames[0]);
+static int nsyscalls = nitems(syscallnames);
 
 /*
  * This is what this particular file uses to keep track of a system call.
diff --git a/usr.bin/truss/i386-linux.c b/usr.bin/truss/i386-linux.c
index 84f1451414b4..5057449fa24e 100644
--- a/usr.bin/truss/i386-linux.c
+++ b/usr.bin/truss/i386-linux.c
@@ -61,8 +61,7 @@ static const char rcsid[] =
 
 #include "linux_syscalls.h"
 
-static int nsyscalls =
-	sizeof(linux_syscallnames) / sizeof(linux_syscallnames[0]);
+static int nsyscalls = nitems(linux_syscallnames);
 
 /*
  * This is what this particular file uses to keep track of a system call.
@@ -309,8 +308,7 @@ i386_linux_syscall_exit(struct trussinfo *trussinfo, int syscall_num __unused)
 	 * but that complicates things considerably.
 	 */
 	if (errorp) {
-		for (i = 0;
-		    (size_t)i < sizeof(bsd_to_linux_errno) / sizeof(int); i++) {
+		for (i = 0; (size_t)i < nitems(bsd_to_linux_errno); i++) {
 			if (retval == bsd_to_linux_errno[i])
 				break;
 		}
diff --git a/usr.bin/truss/mips-fbsd.c b/usr.bin/truss/mips-fbsd.c
index 71e9efabdf31..328269588e8f 100644
--- a/usr.bin/truss/mips-fbsd.c
+++ b/usr.bin/truss/mips-fbsd.c
@@ -68,7 +68,7 @@ static const char rcsid[] =
 
 #include "syscalls.h"
 
-static int nsyscalls = sizeof(syscallnames) / sizeof(syscallnames[0]);
+static int nsyscalls = nitems(syscallnames);
 
 /*
  * This is what this particular file uses to keep track of a system call.
diff --git a/usr.bin/truss/powerpc-fbsd.c b/usr.bin/truss/powerpc-fbsd.c
index 990da29c143e..7215dca1dc16 100644
--- a/usr.bin/truss/powerpc-fbsd.c
+++ b/usr.bin/truss/powerpc-fbsd.c
@@ -68,7 +68,7 @@ static const char rcsid[] =
 #include "syscalls.h"
 #endif
 
-static int nsyscalls = sizeof(syscallnames) / sizeof(syscallnames[0]);
+static int nsyscalls = nitems(syscallnames);
 
 /*
  * This is what this particular file uses to keep track of a system call.
diff --git a/usr.bin/truss/powerpc64-fbsd.c b/usr.bin/truss/powerpc64-fbsd.c
index 9d5cbd9199b9..6509e6546b5f 100644
--- a/usr.bin/truss/powerpc64-fbsd.c
+++ b/usr.bin/truss/powerpc64-fbsd.c
@@ -63,7 +63,7 @@ static const char rcsid[] =
 
 #include "syscalls.h"
 
-static int nsyscalls = sizeof(syscallnames) / sizeof(syscallnames[0]);
+static int nsyscalls = nitems(syscallnames);
 
 /*
  * This is what this particular file uses to keep track of a system call.
diff --git a/usr.bin/truss/sparc64-fbsd.c b/usr.bin/truss/sparc64-fbsd.c
index 3c6de5fe2fa1..f415c9610922 100644
--- a/usr.bin/truss/sparc64-fbsd.c
+++ b/usr.bin/truss/sparc64-fbsd.c
@@ -69,7 +69,7 @@ static const char rcsid[] =
 
 #include "syscalls.h"
 
-static int nsyscalls = sizeof(syscallnames) / sizeof(syscallnames[0]);
+static int nsyscalls = nitems(syscallnames);
 
 /*
  * This is what this particular file uses to keep track of a system call.