diff --git a/+stdlib/expanduser.m b/+stdlib/expanduser.m
index f419b39..485937e 100644
--- a/+stdlib/expanduser.m
+++ b/+stdlib/expanduser.m
@@ -15,14 +15,14 @@
 
 e = p;
 
-if ~all(startsWith(e, "~")) || (all(strlength(e) > 1) && ~all(startsWith(e, "~/")))
+if ~startsWith(e, "~") || (strlength(e) > 1 && ~startsWith(e, "~/"))
   return
 end
 
 home = stdlib.homedir(use_java);
 
 if ~isempty(home)
-  e = stdlib.join(home, extractAfter(e, 1));
+  e = stdlib.join(home, strip(extractAfter(e, 1), "left", "/"));
 end
 
 end %function
diff --git a/+stdlib/join.m b/+stdlib/join.m
index b0e7c6b..3463e3a 100644
--- a/+stdlib/join.m
+++ b/+stdlib/join.m
@@ -1,10 +1,43 @@
-function p = join(a, b)
+function p = join(a, b, use_java)
 %% JOIN: join two paths with posix file separator
 arguments
   a (1,1) string
   b (1,1) string
+  use_java (1,1) logical = false
 end
 
-p = stdlib.posix(fullfile(a, b));
+if a == "" && b == ""
+  p = "";
+  return
+end
+
+a = stdlib.posix(a);
+b = stdlib.posix(b);
+
+if a == ""
+  p = b;
+  return
+end
+
+if b == ""
+  p = a;
+  return
+end
+
+
+if use_java
+
+p = stdlib.posix(java.io.File(stdlib.normalize(a, true)).toPath().resolve(stdlib.normalize(b, true)));
+
+else
+
+if startsWith(b, "/") || (ispc && stdlib.is_absolute(b))
+  p = b;
+  return
+end
+
+p = stdlib.normalize(a) + "/" + stdlib.normalize(b);
+
+end
 
 end
diff --git a/+stdlib/parent.m b/+stdlib/parent.m
index 72945ba..b664f89 100644
--- a/+stdlib/parent.m
+++ b/+stdlib/parent.m
@@ -10,6 +10,15 @@
   % java is about 10x slower than intrinsic
   p = java.io.File(p).getParent();
 else
+  p = stdlib.posix(p);
+  % drop duplicated slashes in the parent path
+  p = regexprep(p, "//+", "/");
+
+  if ispc && any(strlength(p) == [2,3]) && isletter(extractBetween(p, 1, 1)) && extractBetween(p, 2, 2) == ":"
+    % 2 or 3 char drive letter
+    p = stdlib.root(p);
+    return
+  end
   % have to drop_slash on input to get expected parent path
   p = strip(stdlib.posix(p), "right", "/");
   j = strfind(p, "/");
diff --git a/test/TestFilePure.m b/test/TestFilePure.m
index a5a90c0..8496347 100644
--- a/test/TestFilePure.m
+++ b/test/TestFilePure.m
@@ -17,8 +17,12 @@
 sub_is_subdir
 ref_is_subdir
 
-in_parent = {"", ".", "..", "../..", "a/b", "a/b/", "ab/.parent", "ab/.parent.txt", "a/b/../.parent.txt"}
-ref_parent = {".", ".", ".", "..",   "a",   "a",    "ab",         "ab",             "a/b/.."}
+in_parent
+ref_parent
+
+in_join = {"", "a", "", "a/b/", "/", "", "a", "a//", "a/b/../", "a/b", "ab/cd"}
+other_join = {"", "", "b", "c/", "", "/", "b//", "b//", "c/d/../", "c/d", "/ef"}
+ref_join = {"", "a", "b", "a/b/c", "/", "/", "a/b", "a/b", "a/c", "a/b/c/d", "/ef"}
 
 in_suffix = {"", "/foo/bar/baz", "/foo/bar/baz/", "foo/bar/baz.txt", "foo/bar/baz.txt.gz", ".stat", ".stat.txt"}
 ref_suffix = {"", "", "", ".txt", ".gz", ".stat", ".txt"}
@@ -37,11 +41,14 @@
 end
 
 methods (TestParameterDefinition, Static)
-function [base_relative_to, other_relative_to, ref_relative_to, ref_proximate_to, in_root, ref_root] = init_relative_to(classToTest) %#ok<INUSD>
+function [base_relative_to, other_relative_to, ref_relative_to, ref_proximate_to, in_root, ref_root, in_parent, ref_parent] = init_relative_to(classToTest) %#ok<INUSD>
 
 in_root = {"", "a/b", "./a/b", "../a/b", "/etc", "c:/etc"};
 ref_root = {"", "", "", "", "/", ""};
 
+in_parent = {"", ".", "..", "../..", "a/", "a/b", "a/b/", "ab/.parent", "ab/.parent.txt", "a/b/../.parent.txt", "a/////b////c", "c:/", "c:\", "c:/a/b", "c:\a/b"};
+ref_parent = {".", ".", ".", "..",   ".",  "a",   "a",    "ab",         "ab",             "a/b/..",             "a/b",          ".",    ".",    "c:/a",     "c:\a"};
+
 if ispc
 
 base_relative_to = {'', 'Hello', 'Hello', ...
@@ -55,6 +62,11 @@
 ref_proximate_to = ref_relative_to;
 ref_proximate_to{end} = other_relative_to{end};
 
+ref_parent{12} = "c:/";
+ref_parent{13} = "c:/";
+ref_parent{14} = "c:/a";
+ref_parent{15} = "c:/a";
+
 ref_root{5} = "";
 ref_root{6} = "c:/";
 
@@ -158,6 +170,11 @@ function test_posix(tc)
 end
 
 
+function test_join(tc, in_join, other_join, ref_join)
+tc.verifyEqual(stdlib.join(in_join, other_join), ref_join)
+end
+
+
 function test_filename(tc, in_filename, ref_filename)
 tc.verifyEqual(stdlib.filename(in_filename), string(ref_filename))
 end