diff --git a/Makefile b/Makefile
index 423e315..501f65a 100644
--- a/Makefile
+++ b/Makefile
@@ -25,7 +25,7 @@
 DIFF    = diff
 PREFIX  ?= /usr/local
 MANDIR  ?= $(PREFIX)/share/man
-CFLAGS  ?= -Os -Wall -Werror
+CFLAGS  ?= -Os -Wall -Werror -Wshadow
 EXPORTDIR ?= .
 
 OS_ARCH	= $(shell uname)
diff --git a/cbtable.c b/cbtable.c
index 2bc1bfa..2611a62 100644
--- a/cbtable.c
+++ b/cbtable.c
@@ -50,7 +50,7 @@
 	volatile union {
 		uint8_t byte[2];
 		uint16_t word;
-	} value;
+	} chksum;
 	unsigned long sum;
 	unsigned long i;
 
@@ -72,10 +72,10 @@
 			sum = (sum + (sum >> 16)) & 0xFFFF;
 		}
 	}
-	value.byte[0] = sum & 0xff;
-	value.byte[1] = (sum >> 8) & 0xff;
+	chksum.byte[0] = sum & 0xff;
+	chksum.byte[1] = (sum >> 8) & 0xff;
 
-	return (~value.word) & 0xFFFF;
+	return (~chksum.word) & 0xFFFF;
 }
 
 #define for_each_lbrec(head, rec) \
diff --git a/cli_classic.c b/cli_classic.c
index d3e7a15..6cb0578 100644
--- a/cli_classic.c
+++ b/cli_classic.c
@@ -150,7 +150,6 @@
 
 	if (argc > 1) {
 		/* Yes, print them. */
-		int i;
 		printf_debug("The arguments are:\n");
 		for (i = 1; i < argc; ++i)
 			printf_debug("%s\n", argv[i]);
diff --git a/flash.h b/flash.h
index 069b903..9a25c70 100644
--- a/flash.h
+++ b/flash.h
@@ -297,7 +297,6 @@
 
 extern uint32_t io_base_addr;
 extern struct pci_access *pacc;
-extern struct pci_filter filter;
 extern struct pci_dev *pcidev_dev;
 struct pcidev_status {
 	uint16_t vendor_id;
diff --git a/hwaccess.h b/hwaccess.h
index 2bc2927..0729226 100644
--- a/hwaccess.h
+++ b/hwaccess.h
@@ -46,12 +46,12 @@
   #include <machine/cpufunc.h>
   #define off64_t off_t
   #define lseek64 lseek
-  #define OUTB(x, y) do { u_int tmp = (y); outb(tmp, (x)); } while (0)
-  #define OUTW(x, y) do { u_int tmp = (y); outw(tmp, (x)); } while (0)
-  #define OUTL(x, y) do { u_int tmp = (y); outl(tmp, (x)); } while (0)
-  #define INB(x) __extension__ ({ u_int tmp = (x); inb(tmp); })
-  #define INW(x) __extension__ ({ u_int tmp = (x); inw(tmp); })
-  #define INL(x) __extension__ ({ u_int tmp = (x); inl(tmp); })
+  #define OUTB(x, y) do { u_int outb_tmp = (y); outb(outb_tmp, (x)); } while (0)
+  #define OUTW(x, y) do { u_int outw_tmp = (y); outw(outw_tmp, (x)); } while (0)
+  #define OUTL(x, y) do { u_int outl_tmp = (y); outl(outl_tmp, (x)); } while (0)
+  #define INB(x) __extension__ ({ u_int inb_tmp = (x); inb(inb_tmp); })
+  #define INW(x) __extension__ ({ u_int inw_tmp = (x); inw(inw_tmp); })
+  #define INL(x) __extension__ ({ u_int inl_tmp = (x); inl(inl_tmp); })
 #else
 #if defined(__DARWIN__)
     #include <DirectIO/darwinio.h>