diff --git a/sys/src/cmd/abaco/util.c b/sys/src/cmd/abaco/util.c
index f2aae8324..9d4fae1b8 100644
--- a/sys/src/cmd/abaco/util.c
+++ b/sys/src/cmd/abaco/util.c
@@ -676,7 +676,7 @@ execproc(void *v)
 	}
 	if(!procstderr)
 		close(2);
-	procexecl(e->sync, "/bin/rc", "rc", "-c", e->cmd, 0);
+	procexecl(e->sync, "/bin/rc", "rc", "-c", e->cmd, nil);
 	error("can't exec");
 }
 
diff --git a/sys/src/cmd/audio/flacdec/flacdec.c b/sys/src/cmd/audio/flacdec/flacdec.c
index 88f596508..020f3f087 100644
--- a/sys/src/cmd/audio/flacdec/flacdec.c
+++ b/sys/src/cmd/audio/flacdec/flacdec.c
@@ -55,7 +55,7 @@ decoutput(FLAC__StreamDecoder *dec, FLAC__Frame *frame, FLAC__int32 *buffer[], v
 			dup2(pfd[1], 0);
 			close(pfd[1]);
 			close(pfd[0]);
-			execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, 0);
+			execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, nil);
 			fprintf(stderr, "Error executing converter\n");
 			exit(1);
 		}
diff --git a/sys/src/cmd/audio/mp3dec/main.c b/sys/src/cmd/audio/mp3dec/main.c
index 1aef43e0c..ee90ce0bd 100644
--- a/sys/src/cmd/audio/mp3dec/main.c
+++ b/sys/src/cmd/audio/mp3dec/main.c
@@ -61,7 +61,7 @@ output(void *, struct mad_header const* header, struct mad_pcm *pcm)
 			dup(pfd[1], 0);
 			close(pfd[1]);
 			close(pfd[0]);
-			execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, 0);
+			execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, nil);
 			sysfatal("exec: %r");
 		}
 		close(pfd[1]);
diff --git a/sys/src/cmd/audio/oggdec/oggdec.c b/sys/src/cmd/audio/oggdec/oggdec.c
index af9283f89..ec4beb17f 100644
--- a/sys/src/cmd/audio/oggdec/oggdec.c
+++ b/sys/src/cmd/audio/oggdec/oggdec.c
@@ -61,7 +61,7 @@ output(float **pcm, int samples, vorbis_info *vi)
 			dup2(pfd[1], 0);
 			close(pfd[1]);
 			close(pfd[0]);
-			execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, 0);
+			execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, nil);
 			fprintf(stderr, "Error executing converter\n");
 			exit(1);
 		}
diff --git a/sys/src/cmd/audio/sundec/sundec.c b/sys/src/cmd/audio/sundec/sundec.c
index 345bcc03e..977a9985b 100644
--- a/sys/src/cmd/audio/sundec/sundec.c
+++ b/sys/src/cmd/audio/sundec/sundec.c
@@ -56,7 +56,7 @@ main(int, char *argv[])
 	}
 	if(len > 0){
 		snprint(buf, sizeof(buf), "%lud", len);
-		execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, "-l", buf, 0);
+		execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, "-l", buf, nil);
 	} else
-		execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, 0);
+		execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, nil);
 }
diff --git a/sys/src/cmd/audio/wavdec/wavdec.c b/sys/src/cmd/audio/wavdec/wavdec.c
index 9b116c550..02e44e7a2 100644
--- a/sys/src/cmd/audio/wavdec/wavdec.c
+++ b/sys/src/cmd/audio/wavdec/wavdec.c
@@ -97,5 +97,5 @@ main(int, char *argv[])
 		sysfatal("wave format (0x%lux) not supported", (ulong)wav.fmt);
 	}
 	snprint(buf, sizeof(buf), "%lud", len);
-	execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, "-l", buf, 0);
+	execl("/bin/audio/pcmconv", "pcmconv", "-i", fmt, "-l", buf, nil);
 }
diff --git a/sys/src/cmd/mothra/mothra.c b/sys/src/cmd/mothra/mothra.c
index c15bb4a80..c1faf8ffd 100644
--- a/sys/src/cmd/mothra/mothra.c
+++ b/sys/src/cmd/mothra/mothra.c
@@ -809,7 +809,7 @@ void filter(int fd, char *cmd){
 		break;
 	case 0:
 		dupfds(fd, 1, 2, -1);
-		execl("/bin/rc", "rc", "-c", cmd, 0);
+		execl("/bin/rc", "rc", "-c", cmd, nil);
 		_exits(0);
 	}
 	close(fd);
diff --git a/sys/src/cmd/vnc/wsys.c b/sys/src/cmd/vnc/wsys.c
index 08e0e1946..9e5c1cd0a 100644
--- a/sys/src/cmd/vnc/wsys.c
+++ b/sys/src/cmd/vnc/wsys.c
@@ -195,8 +195,8 @@ tcs(int fd0, int fd1)
 		}
 		close(pfd[0]);
 		close(pfd[1]);
-		execl("/bin/tcs", "tcs", fd0 < 0 ? "-f" : "-t", charset, 0);
-		execl("/bin/cat", "cat", 0);
+		execl("/bin/tcs", "tcs", fd0 < 0 ? "-f" : "-t", charset, nil);
+		execl("/bin/cat", "cat", nil);
 		_exits(0);
 	}
 	close(pfd[0]);