diff --git a/include/libbb.h b/include/libbb.h
index 14a16674c..fd61517c2 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1359,9 +1359,9 @@ enum {
 //procps_status_t* alloc_procps_scan(void) FAST_FUNC;
 void free_procps_scan(procps_status_t* sp) FAST_FUNC;
 procps_status_t* procps_scan(procps_status_t* sp, int flags) FAST_FUNC;
-/* Format cmdline (up to col chars) into char buf[col+1] */
+/* Format cmdline (up to col chars) into char buf[size] */
 /* Puts [comm] if cmdline is empty (-> process is a kernel thread) */
-void read_cmdline(char *buf, int col, unsigned pid, const char *comm) FAST_FUNC;
+void read_cmdline(char *buf, int size, unsigned pid, const char *comm) FAST_FUNC;
 pid_t *find_pid_by_name(const char* procName) FAST_FUNC;
 pid_t *pidlist_reverse(pid_t *pidList) FAST_FUNC;
 
diff --git a/libbb/procps.c b/libbb/procps.c
index 9a8e42df7..974661785 100644
--- a/libbb/procps.c
+++ b/libbb/procps.c
@@ -464,18 +464,19 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
 
 void FAST_FUNC read_cmdline(char *buf, int col, unsigned pid, const char *comm)
 {
-	ssize_t sz;
+	int sz;
 	char filename[sizeof("/proc//cmdline") + sizeof(int)*3];
 
 	sprintf(filename, "/proc/%u/cmdline", pid);
-	sz = open_read_close(filename, buf, col);
+	sz = open_read_close(filename, buf, col - 1);
 	if (sz > 0) {
 		buf[sz] = '\0';
 		while (--sz >= 0 && buf[sz] == '\0')
 			continue;
-		while (--sz >= 0)
+		do {
 			if ((unsigned char)(buf[sz]) < ' ')
 				buf[sz] = ' ';
+		} while (--sz >= 0);
 	} else {
 		snprintf(buf, col, "[%s]", comm);
 	}
diff --git a/procps/ps.c b/procps/ps.c
index 4a6b60bdc..6523f0f38 100644
--- a/procps/ps.c
+++ b/procps/ps.c
@@ -186,7 +186,7 @@ static void func_comm(char *buf, int size, const procps_status_t *ps)
 
 static void func_args(char *buf, int size, const procps_status_t *ps)
 {
-	read_cmdline(buf, size, ps->pid, ps->comm);
+	read_cmdline(buf, size+1, ps->pid, ps->comm);
 }
 
 static void func_pid(char *buf, int size, const procps_status_t *ps)
diff --git a/procps/top.c b/procps/top.c
index 92360a005..7133e5c99 100644
--- a/procps/top.c
+++ b/procps/top.c
@@ -617,7 +617,7 @@ static NOINLINE void display_process_list(int lines_rem, int scr_width)
 #endif
 		);
 		if ((int)(col + 1) < scr_width)
-			read_cmdline(line_buf + col, scr_width - col - 1, s->pid, s->comm);
+			read_cmdline(line_buf + col, scr_width - col, s->pid, s->comm);
 		fputs(line_buf, stdout);
 		/* printf(" %d/%d %lld/%lld", s->pcpu, total_pcpu,
 			cur_jif.busy - prev_jif.busy, cur_jif.total - prev_jif.total); */