diff --git a/tests/dumptrees.c b/tests/dumptrees.c
index f1e0ea9..08967b3 100644
--- a/tests/dumptrees.c
+++ b/tests/dumptrees.c
@@ -32,7 +32,7 @@ static struct {
 
 int main(int argc, char *argv[])
 {
-	int i;
+	unsigned int i;
 
 	if (argc != 2) {
 	    fprintf(stderr, "Missing output directory argument\n");
diff --git a/tests/fs_tree1.c b/tests/fs_tree1.c
index dff3880..978f6a3 100644
--- a/tests/fs_tree1.c
+++ b/tests/fs_tree1.c
@@ -54,7 +54,7 @@ static void mkfile(const char *name, void *data, size_t len)
 	rc = write(fd, data, len);
 	if (rc < 0)
 		FAIL("write(\"%s\"): %s", name, strerror(errno));
-	if (rc != len)
+	if ((unsigned)rc != len)
 		FAIL("write(\"%s\"): short write", name);
 	
 	rc = close(fd);
diff --git a/tests/get_name.c b/tests/get_name.c
index 5a35103..d20bf30 100644
--- a/tests/get_name.c
+++ b/tests/get_name.c
@@ -34,12 +34,14 @@ static void check_name(void *fdt, const char *path)
 		       offset, getname, len);
 	if (!getname)
 		FAIL("fdt_get_name(%d): %s", offset, fdt_strerror(len));
+	if (len < 0)
+		FAIL("negative name length (%d) for returned node name\n", len);
 
 	if (strcmp(getname, checkname) != 0)
 		FAIL("fdt_get_name(%s) returned \"%s\" instead of \"%s\"",
 		     path, getname, checkname);
 
-	if (len != strlen(getname))
+	if ((unsigned)len != strlen(getname))
 		FAIL("fdt_get_name(%s) returned length %d instead of %zd",
 		     path, len, strlen(getname));
 
diff --git a/tests/integer-expressions.c b/tests/integer-expressions.c
index 6f33d81..2f164d9 100644
--- a/tests/integer-expressions.c
+++ b/tests/integer-expressions.c
@@ -59,7 +59,7 @@ int main(int argc, char *argv[])
 	void *fdt;
 	const fdt32_t *res;
 	int reslen;
-	int i;
+	unsigned int i;
 
 	test_init(argc, argv);
 
diff --git a/tests/nopulate.c b/tests/nopulate.c
index 2ae1753..e06a0b3 100644
--- a/tests/nopulate.c
+++ b/tests/nopulate.c
@@ -43,7 +43,8 @@ static int nopulate_struct(char *buf, const char *fdt)
 int main(int argc, char *argv[])
 {
 	char *fdt, *fdt2, *buf;
-	int newsize, struct_start, struct_end_old, struct_end_new, delta;
+	int newsize, struct_end_old, struct_end_new, delta;
+	unsigned int struct_start;
 	const char *inname;
 	char outname[PATH_MAX];
 
diff --git a/tests/overlay.c b/tests/overlay.c
index 91afa72..f3dd310 100644
--- a/tests/overlay.c
+++ b/tests/overlay.c
@@ -35,7 +35,11 @@ static int fdt_getprop_u32_by_poffset(void *fdt, const char *path,
 		return node_off;
 
 	val = fdt_getprop(fdt, node_off, name, &len);
-	if (!val || (len < (sizeof(uint32_t) * (poffset + 1))))
+	if (val && len < 0)
+		FAIL("fdt_getprop() returns negative length");
+	if (!val && len < 0)
+		return len;
+	if (!val || ((unsigned)len < (sizeof(uint32_t) * (poffset + 1))))
 		return -FDT_ERR_NOTFOUND;
 
 	*out = fdt32_to_cpu(*(val + poffset));
diff --git a/tests/phandle_format.c b/tests/phandle_format.c
index d00618f..0febb32 100644
--- a/tests/phandle_format.c
+++ b/tests/phandle_format.c
@@ -45,7 +45,7 @@ int main(int argc, char *argv[])
 		FAIL("fdt_path_offset(/node4): %s", fdt_strerror(n4));
 
 	h4 = fdt_get_phandle(fdt, n4);
-	if ((h4 == 0) || (h4 == -1))
+	if ((h4 == 0) || (h4 == ~0U))
 		FAIL("/node4 has bad phandle 0x%x\n", h4);
 
 	if (phandle_format & PHANDLE_LEGACY)
diff --git a/tests/property_iterate.c b/tests/property_iterate.c
index 9a67f49..0b6af9b 100644
--- a/tests/property_iterate.c
+++ b/tests/property_iterate.c
@@ -23,7 +23,7 @@ static void test_node(void *fdt, int parent_offset)
 	uint32_t properties;
 	const fdt32_t *prop;
 	int offset, property;
-	int count;
+	unsigned int count;
 	int len;
 
 	/*
diff --git a/tests/references.c b/tests/references.c
index d18e722..cb1daaa 100644
--- a/tests/references.c
+++ b/tests/references.c
@@ -106,7 +106,7 @@ int main(int argc, char *argv[])
 	if ((h4 == 0x2000) || (h4 == 0x1) || (h4 == 0))
 		FAIL("/node4 has bad phandle, 0x%x", h4);
 
-	if ((h5 == 0) || (h5 == -1))
+	if ((h5 == 0) || (h5 == ~0U))
 		FAIL("/node5 has bad phandle, 0x%x", h5);
 	if ((h5 == h4) || (h5 == h2) || (h5 == h1))
 		FAIL("/node5 has duplicate phandle, 0x%x", h5);
diff --git a/tests/set_name.c b/tests/set_name.c
index a62cb58..5020305 100644
--- a/tests/set_name.c
+++ b/tests/set_name.c
@@ -39,7 +39,11 @@ static void check_set_name(void *fdt, const char *path, const char *newname)
 		FAIL("fdt_get_name(%s) returned \"%s\" instead of \"%s\"",
 		     path, getname, oldname);
 
-	if (len != strlen(getname))
+	if (len < 0)
+		FAIL("fdt_get_name(%s) returned negative length: %d",
+		     path, len);
+
+	if ((unsigned)len != strlen(getname))
 		FAIL("fdt_get_name(%s) returned length %d instead of %zd",
 		     path, len, strlen(getname));
 
@@ -51,12 +55,14 @@ static void check_set_name(void *fdt, const char *path, const char *newname)
 	getname = fdt_get_name(fdt, offset, &len);
 	if (!getname)
 		FAIL("fdt_get_name(%d): %s", offset, fdt_strerror(len));
+	if (len < 0)
+		FAIL("negative name length (%d) for returned node name\n", len);
 
 	if (strcmp(getname, newname) != 0)
 		FAIL("fdt_get_name(%s) returned \"%s\" instead of \"%s\"",
 		     path, getname, newname);
 
-	if (len != strlen(getname))
+	if ((unsigned)len != strlen(getname))
 		FAIL("fdt_get_name(%s) returned length %d instead of %zd",
 		     path, len, strlen(getname));
 }
diff --git a/tests/subnode_iterate.c b/tests/subnode_iterate.c
index 2dc9b2d..2553a51 100644
--- a/tests/subnode_iterate.c
+++ b/tests/subnode_iterate.c
@@ -23,7 +23,7 @@ static void test_node(void *fdt, int parent_offset)
 	uint32_t subnodes;
 	const fdt32_t *prop;
 	int offset;
-	int count;
+	unsigned int count;
 	int len;
 
 	/* This property indicates the number of subnodes to expect */
diff --git a/tests/tests.h b/tests/tests.h
index 1017366..bf8f23c 100644
--- a/tests/tests.h
+++ b/tests/tests.h
@@ -83,7 +83,7 @@ void cleanup(void);
 void check_mem_rsv(void *fdt, int n, uint64_t addr, uint64_t size);
 
 void check_property(void *fdt, int nodeoffset, const char *name,
-		    int len, const void *val);
+		    unsigned int len, const void *val);
 #define check_property_cell(fdt, nodeoffset, name, val) \
 	({ \
 		fdt32_t x = cpu_to_fdt32(val);			      \
diff --git a/tests/testutils.c b/tests/testutils.c
index 5e494c5..10129c0 100644
--- a/tests/testutils.c
+++ b/tests/testutils.c
@@ -88,7 +88,7 @@ void check_mem_rsv(void *fdt, int n, uint64_t addr, uint64_t size)
 }
 
 void check_property(void *fdt, int nodeoffset, const char *name,
-		    int len, const void *val)
+		    unsigned int len, const void *val)
 {
 	const struct fdt_property *prop;
 	int retlen, namelen;
@@ -101,6 +101,9 @@ void check_property(void *fdt, int nodeoffset, const char *name,
 	if (! prop)
 		FAIL("Error retrieving \"%s\" pointer: %s", name,
 		     fdt_strerror(retlen));
+	if (retlen < 0)
+		FAIL("negative name length (%d) for returned property\n",
+		     retlen);
 
 	tag = fdt32_to_cpu(prop->tag);
 	nameoff = fdt32_to_cpu(prop->nameoff);
@@ -112,13 +115,16 @@ void check_property(void *fdt, int nodeoffset, const char *name,
 	propname = fdt_get_string(fdt, nameoff, &namelen);
 	if (!propname)
 		FAIL("Couldn't get property name: %s", fdt_strerror(namelen));
-	if (namelen != strlen(propname))
+	if (namelen < 0)
+		FAIL("negative name length (%d) for returned string\n",
+		     namelen);
+	if ((unsigned)namelen != strlen(propname))
 		FAIL("Incorrect prop name length: %d instead of %zd",
 		     namelen, strlen(propname));
 	if (!streq(propname, name))
 		FAIL("Property name mismatch \"%s\" instead of \"%s\"",
 		     propname, name);
-	if (proplen != retlen)
+	if (proplen != (unsigned)retlen)
 		FAIL("Length retrieved for \"%s\" by fdt_get_property()"
 		     " differs from stored length (%d != %d)",
 		     name, retlen, proplen);