diff --git a/cbtable.c b/cbtable.c
index dbb2cff..f30a3ae 100644
--- a/cbtable.c
+++ b/cbtable.c
@@ -141,7 +141,7 @@
 
 	};
 
-	return 0;
+	return NULL;
 }
 
 static void find_mainboard(struct lb_record *ptr, unsigned long addr)
diff --git a/chipset_enable.c b/chipset_enable.c
index 6d6008e..0896bce 100644
--- a/chipset_enable.c
+++ b/chipset_enable.c
@@ -1173,7 +1173,7 @@
 
 int chipset_flash_enable(void)
 {
-	struct pci_dev *dev = 0;
+	struct pci_dev *dev = NULL;
 	int ret = -2;		/* Nothing! */
 	int i;
 
diff --git a/cli_classic.c b/cli_classic.c
index 1211989..88b70db 100644
--- a/cli_classic.c
+++ b/cli_classic.c
@@ -116,23 +116,23 @@
 
 	static const char optstring[] = "r:Rw:v:nVEfc:m:l:i:p:Lzh";
 	static const struct option long_options[] = {
-		{"read", 1, 0, 'r'},
-		{"write", 1, 0, 'w'},
-		{"erase", 0, 0, 'E'},
-		{"verify", 1, 0, 'v'},
-		{"noverify", 0, 0, 'n'},
-		{"chip", 1, 0, 'c'},
-		{"mainboard", 1, 0, 'm'},
-		{"verbose", 0, 0, 'V'},
-		{"force", 0, 0, 'f'},
-		{"layout", 1, 0, 'l'},
-		{"image", 1, 0, 'i'},
-		{"list-supported", 0, 0, 'L'},
-		{"list-supported-wiki", 0, 0, 'z'},
-		{"programmer", 1, 0, 'p'},
-		{"help", 0, 0, 'h'},
-		{"version", 0, 0, 'R'},
-		{0, 0, 0, 0}
+		{"read", 1, NULL, 'r'},
+		{"write", 1, NULL, 'w'},
+		{"erase", 0, NULL, 'E'},
+		{"verify", 1, NULL, 'v'},
+		{"noverify", 0, NULL, 'n'},
+		{"chip", 1, NULL, 'c'},
+		{"mainboard", 1, NULL, 'm'},
+		{"verbose", 0, NULL, 'V'},
+		{"force", 0, NULL, 'f'},
+		{"layout", 1, NULL, 'l'},
+		{"image", 1, NULL, 'i'},
+		{"list-supported", 0, NULL, 'L'},
+		{"list-supported-wiki", 0, NULL, 'z'},
+		{"programmer", 1, NULL, 'p'},
+		{"help", 0, NULL, 'h'},
+		{"version", 0, NULL, 'R'},
+		{NULL, 0, NULL, 0}
 	};
 
 	char *filename = NULL;
diff --git a/physmap.c b/physmap.c
index 4641e8e..70156a6 100644
--- a/physmap.c
+++ b/physmap.c
@@ -180,7 +180,7 @@
 		}
 	}
 
-	virt_addr = mmap(0, len, PROT_WRITE | PROT_READ, MAP_SHARED,
+	virt_addr = mmap(NULL, len, PROT_WRITE | PROT_READ, MAP_SHARED,
 			 fd_mem, (off_t)phys_addr);
 	return MAP_FAILED == virt_addr ? ERROR_PTR : virt_addr;
 }
@@ -200,7 +200,7 @@
 		}
 	}
 
-	virt_addr = mmap(0, len, PROT_READ, MAP_SHARED,
+	virt_addr = mmap(NULL, len, PROT_READ, MAP_SHARED,
 			 fd_mem_cached, (off_t)phys_addr);
 	return MAP_FAILED == virt_addr ? ERROR_PTR : virt_addr;
 }
diff --git a/programmer.c b/programmer.c
index 0160867..5c1f963 100644
--- a/programmer.c
+++ b/programmer.c
@@ -30,7 +30,7 @@
 void *fallback_map(const char *descr, unsigned long phys_addr, size_t len)
 {
 	/* FIXME: Should return phys_addr. */
-	return 0;
+	return NULL;
 }
 
 /* No-op/fallback unmap() for programmers which don't need special handling */
diff --git a/serprog.c b/serprog.c
index 2cdfea6..f869b07 100644
--- a/serprog.c
+++ b/serprog.c
@@ -541,7 +541,7 @@
 {
 	if ((sp_max_write_n) && (sp_write_n_bytes))
 		sp_pass_writen();
-	sp_stream_buffer_op(S_CMD_O_EXEC, 0, 0);
+	sp_stream_buffer_op(S_CMD_O_EXEC, 0, NULL);
 	msg_pspew(MSGHEADER "Executed operation buffer of %d bytes\n",
 		     sp_opbuf_usage);
 	sp_opbuf_usage = 0;
diff --git a/udelay.c b/udelay.c
index 153f510..feae827 100644
--- a/udelay.c
+++ b/udelay.c
@@ -45,11 +45,11 @@
 	struct timeval start, end;
 	unsigned long counter = 0;
 	
-	gettimeofday(&start, 0);
+	gettimeofday(&start, NULL);
 	timeusec = 0;
 	
 	while (!timeusec && (++counter < 1000000000)) {
-		gettimeofday(&end, 0);
+		gettimeofday(&end, NULL);
 		timeusec = 1000000 * (end.tv_sec - start.tv_sec) +
 			   (end.tv_usec - start.tv_usec);
 		/* Protect against time going forward too much. */
@@ -68,9 +68,9 @@
 	unsigned long timeusec;
 	struct timeval start, end;
 	
-	gettimeofday(&start, 0);
+	gettimeofday(&start, NULL);
 	myusec_delay(usecs);
-	gettimeofday(&end, 0);
+	gettimeofday(&end, NULL);
 	timeusec = 1000000 * (end.tv_sec - start.tv_sec) +
 		   (end.tv_usec - start.tv_usec);
 	/* Protect against time going forward too much. */