diff --git a/bin/cp/cp.c b/bin/cp/cp.c
--- a/bin/cp/cp.c
+++ b/bin/cp/cp.c
@@ -433,6 +433,8 @@
 				sep = strchr(to.base, '\0');
 				sep[0] = '/';
 				sep[1] = '\0';
+			} else if (strcmp(curr->fts_name, "/") == 0) {
+				/* special case when source is the root directory */
 			} else {
 				/* entering a directory; append its name to to.path */
 				len = snprintf(to.end, END(to.path) - to.end, "%s%s",
@@ -520,6 +522,8 @@
 				if (type == DIR_TO_DNE &&
 				    curr->fts_level == FTS_ROOTLEVEL) {
 					/* this is actually our created root */
+				} else if (strcmp(curr->fts_name, "/") == 0) {
+					/* special case when source is the root directory */
 				} else {
 					while (to.end > to.path && *to.end != '/')
 						to.end--;
@@ -551,7 +555,8 @@
 		/* Not an error but need to remember it happened. */
 		if (to.path[0] == '\0') {
 			/*
-			 * This can happen in two cases:
+			 * This can happen in three cases:
+			 * - The source path is the root directory.
 			 * - DIR_TO_DNE; we created the directory and
 			 *   populated root_stat earlier.
 			 * - FILE_TO_DIR if a source has a trailing slash;
diff --git a/bin/cp/tests/cp_test.sh b/bin/cp/tests/cp_test.sh
--- a/bin/cp/tests/cp_test.sh
+++ b/bin/cp/tests/cp_test.sh
@@ -747,9 +747,23 @@
 	atf_check cmp dir/file dst/file
 }
 
+atf_test_case root
+root_head()
+{
+	atf_set "descr" "Test copying the root directory"
+}
+root_body()
+{
+	atf_check mkdir dst
+	atf_check -s exit:1 \
+	    -e inline:"cp: / is a directory (not copied).\n" \
+	    cp / dst
+}
+
 atf_test_case to_root cleanup
 to_root_head()
 {
+	atf_set "descr" "Test copying to the root directory"
 	atf_set "require.user" "unprivileged"
 }
 to_root_body()
@@ -893,6 +907,7 @@
 	atf_add_test_case to_deaddirlink
 	atf_add_test_case to_link_outside
 	atf_add_test_case dstmode
+	atf_add_test_case root
 	atf_add_test_case to_root
 	atf_add_test_case dirloop
 	atf_add_test_case unrdir