diff --git a/common/including.fs b/common/including.fs
index dc0abf6..beaebe8 100644
--- a/common/including.fs
+++ b/common/including.fs
@@ -55,9 +55,11 @@ internals definitions
 0 value included-files
 
 : path-join { a a# b b# -- a n }
+  b if
+    b c@ [char] / = if 0 to a# then
+  then
   a# b# + { r# } r# cell+ cell+ allocate throw { r }
   2 cells +to r
-  b c@ [char] / = if 0 to a# then
   begin b b# starts./ while
     2 +to b -2 +to b#
     a# b# + to r#
diff --git a/common/including_tests/including_tests.fs b/common/including_tests/including_tests.fs
index d9c74da..eab7385 100644
--- a/common/including_tests/including_tests.fs
+++ b/common/including_tests/including_tests.fs
@@ -53,3 +53,15 @@ e: test-needs
   out: x.fs 2
   out: x.fs 3
 ;e
+
+e: test-path-join
+  also internals
+  s" /foo/bar/" s" /" path-join s" /" str= assert
+  s" /foo/bar/" s" baz" path-join s" /foo/bar/baz" str= assert
+  s" /foo/bar/" s" ./baz" path-join s" /foo/bar/baz" str= assert
+  s" /foo/bar/" s" ../baz" path-join s" /foo/baz" str= assert
+  s" /foo/bar/" s" baz/qux" path-join s" /foo/bar/baz/qux" str= assert
+  s" /foo/bar/" s" ./baz/qux" path-join s" /foo/bar/baz/qux" str= assert
+  s" /foo/bar/" s" " path-join s" /foo/bar/" str= assert
+  s" ./foo/" s" ../bar" path-join s" ./bar" str= assert
+;e