diff --git a/lib/libfdt/fdt.c b/lib/libfdt/fdt.c
index c28fcc1..6cf2fa0 100644
--- a/lib/libfdt/fdt.c
+++ b/lib/libfdt/fdt.c
@@ -134,16 +134,20 @@
 
 const void *fdt_offset_ptr(const void *fdt, int offset, unsigned int len)
 {
-	unsigned absoffset = offset + fdt_off_dt_struct(fdt);
+	unsigned int uoffset = offset;
+	unsigned int absoffset = offset + fdt_off_dt_struct(fdt);
+
+	if (offset < 0)
+		return NULL;
 
 	if (!can_assume(VALID_INPUT))
-		if ((absoffset < offset)
+		if ((absoffset < uoffset)
 		    || ((absoffset + len) < absoffset)
 		    || (absoffset + len) > fdt_totalsize(fdt))
 			return NULL;
 
 	if (can_assume(LATEST) || fdt_version(fdt) >= 0x11)
-		if (((offset + len) < offset)
+		if (((uoffset + len) < uoffset)
 		    || ((offset + len) > fdt_size_dt_struct(fdt)))
 			return NULL;
 
@@ -206,10 +210,11 @@
 
 int fdt_check_node_offset_(const void *fdt, int offset)
 {
-	if (can_assume(VALID_INPUT))
-		return offset;
-	if ((offset < 0) || (offset % FDT_TAGSIZE)
-	    || (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE))
+	if (!can_assume(VALID_INPUT)
+	    && ((offset < 0) || (offset % FDT_TAGSIZE)))
+		return -FDT_ERR_BADOFFSET;
+
+	if (fdt_next_tag(fdt, offset, &offset) != FDT_BEGIN_NODE)
 		return -FDT_ERR_BADOFFSET;
 
 	return offset;
@@ -217,8 +222,11 @@
 
 int fdt_check_prop_offset_(const void *fdt, int offset)
 {
-	if ((offset < 0) || (offset % FDT_TAGSIZE)
-	    || (fdt_next_tag(fdt, offset, &offset) != FDT_PROP))
+	if (!can_assume(VALID_INPUT)
+	    && ((offset < 0) || (offset % FDT_TAGSIZE)))
+		return -FDT_ERR_BADOFFSET;
+
+	if (fdt_next_tag(fdt, offset, &offset) != FDT_PROP)
 		return -FDT_ERR_BADOFFSET;
 
 	return offset;
@@ -306,9 +314,12 @@
 
 int fdt_move(const void *fdt, void *buf, int bufsize)
 {
+	if (!can_assume(VALID_INPUT) && bufsize < 0)
+		return -FDT_ERR_NOSPACE;
+
 	FDT_RO_PROBE(fdt);
 
-	if (fdt_totalsize(fdt) > bufsize)
+	if (fdt_totalsize(fdt) > (unsigned int)bufsize)
 		return -FDT_ERR_NOSPACE;
 
 	memmove(buf, fdt, fdt_totalsize(fdt));