diff --git a/Makefile b/Makefile
index 10ff447..44de5f8 100644
--- a/Makefile
+++ b/Makefile
@@ -8,7 +8,7 @@ all: gimginfo gimgfixcmd gimgxor gimgunlock gimgch gimgextract cmdc
 gimginfo: gimginfo.o $(GIMGLIB_OBJS)
 
 gimgfixcmd: gimgfixcmd.o cmdlib.o $(GIMGLIB_OBJS)
-	$(CC) -o $@ -lm $^
+	$(CC) -o $@ $^ -lm
 
 gimgxor: gimgxor.o
 
@@ -19,7 +19,7 @@ gimgch: gimgch.o
 gimgextract: gimgextract.o
 
 cmdc: cmdc.o
-	$(CC) -o $@ -lm $<
+	$(CC) -o $@ $< -lm
 
 .PHONY: clean
 clean:
diff --git a/cmdlib.c b/cmdlib.c
index 2d3439f..3aad32d 100644
--- a/cmdlib.c
+++ b/cmdlib.c
@@ -12,7 +12,7 @@ short *cmd_devs = NULL;
 int cmd_init (const char *path)
 {
 	FILE *fp = fopen(path, "rb");
-	if (fopen == NULL) {
+	if (fp == NULL) {
 		printf("cannot open %s\n", path);
 		goto errout;
 	}
diff --git a/gimglib.h b/gimglib.h
index 275fb42..6a5e197 100644
--- a/gimglib.h
+++ b/gimglib.h
@@ -17,6 +17,7 @@
 # include <stdlib.h>
 # include <assert.h>
 # include <string.h>
+# include <strings.h>
 # include <sys/mman.h>
 # include <sys/stat.h>
 # include <unistd.h>
diff --git a/gimgunlock.c b/gimgunlock.c
index d2e33d9..3ebcb19 100644
--- a/gimgunlock.c
+++ b/gimgunlock.c
@@ -71,9 +71,9 @@ int read_byte_at (FILE *fp, unsigned long offset)
 	return getc(fp);
 }
 
-int read_2byte_at (FILE *fp, unsigned long offset)
+unsigned int read_2byte_at (FILE *fp, unsigned long offset)
 {
-	int n = 0;
+	unsigned int n = 0;
 	if (fseek(fp, offset, SEEK_SET)) {
 		perror(NULL);
 		exit(1);
@@ -87,7 +87,7 @@ int read_2byte_at (FILE *fp, unsigned long offset)
 
 unsigned int read_4byte_at (FILE *fp, unsigned long offset)
 {
-	int n = 0;
+	unsigned int n = 0;
 	if (fseek(fp, offset, SEEK_SET)) {
 		perror(NULL);
 		exit(1);
diff --git a/sf_gmp.c b/sf_gmp.c
index 14620d0..8dc9992 100644
--- a/sf_gmp.c
+++ b/sf_gmp.c
@@ -18,7 +18,7 @@ void dump_gmp (struct subfile_struct *sf)
 	printf("unknown_02d: 0x%x\n", header->unknown_02d);
 
 	if (header->comm.hlen > sizeof(struct garmin_gmp))
-		printf("from 0x%x to 0x%x (0x%x bytes): %s\n",
+		printf("from 0x%lx to 0x%x (0x%lx bytes): %s\n",
 				sizeof(struct garmin_gmp), header->comm.hlen - 1,
 				header->comm.hlen - sizeof(struct garmin_gmp),
 				dump_unknown_bytes((uint8_t *)header + sizeof(struct garmin_gmp), header->comm.hlen - sizeof(struct garmin_gmp)));