diff --git a/testsuite/modulefiles.deps/vmod1/1 b/testsuite/modulefiles.deps/vmod1/1
new file mode 100644
index 00000000..60dd2e9d
--- /dev/null
+++ b/testsuite/modulefiles.deps/vmod1/1
@@ -0,0 +1,2 @@
+#%Module
+conflict vmod1
diff --git a/testsuite/modulefiles.deps/vmod1/2 b/testsuite/modulefiles.deps/vmod1/2
new file mode 100644
index 00000000..60dd2e9d
--- /dev/null
+++ b/testsuite/modulefiles.deps/vmod1/2
@@ -0,0 +1,2 @@
+#%Module
+conflict vmod1
diff --git a/testsuite/modulefiles.deps/vmod2/.modulerc b/testsuite/modulefiles.deps/vmod2/.modulerc
new file mode 100644
index 00000000..ce6933c2
--- /dev/null
+++ b/testsuite/modulefiles.deps/vmod2/.modulerc
@@ -0,0 +1,2 @@
+#%Module
+module-version vmod2/1 default
diff --git a/testsuite/modulefiles.deps/vmod2/1 b/testsuite/modulefiles.deps/vmod2/1
new file mode 100644
index 00000000..b118c0d8
--- /dev/null
+++ b/testsuite/modulefiles.deps/vmod2/1
@@ -0,0 +1,2 @@
+#%Module
+conflict vmod2
diff --git a/testsuite/modulefiles.deps/vmod2/2 b/testsuite/modulefiles.deps/vmod2/2
new file mode 100644
index 00000000..6ea46042
--- /dev/null
+++ b/testsuite/modulefiles.deps/vmod2/2
@@ -0,0 +1,3 @@
+#%Module
+prereq vmod1/2
+conflict vmod2
diff --git a/testsuite/modulefiles.deps/vmod3/1 b/testsuite/modulefiles.deps/vmod3/1
new file mode 100644
index 00000000..9d3d6da2
--- /dev/null
+++ b/testsuite/modulefiles.deps/vmod3/1
@@ -0,0 +1,3 @@
+#%Module
+prereq vmod2/2 vmod2
+conflict vmod3
diff --git a/testsuite/modulefiles.deps/vmod3/2 b/testsuite/modulefiles.deps/vmod3/2
new file mode 100644
index 00000000..31d7aa4e
--- /dev/null
+++ b/testsuite/modulefiles.deps/vmod3/2
@@ -0,0 +1,3 @@
+#%Module
+prereq vmod2/2
+conflict vmod3
diff --git a/testsuite/modules.50-cmds/377-error.exp b/testsuite/modules.50-cmds/377-error.exp
index 9597c3df..2367da86 100644
--- a/testsuite/modules.50-cmds/377-error.exp
+++ b/testsuite/modules.50-cmds/377-error.exp
@@ -829,6 +829,29 @@ testouterr_cmd_re sh {reload} ERR [join $tserr \n]
 testouterr_cmd_re sh {reload --force} ERR [join $tserr \n]
 
 
+#
+# Error message test of failed dependency load, which is solved by the load
+# of an alternative requirement (issue #509)
+#
+
+unsetenv_var __MODULES_LMTAG
+unsetenv_var __MODULES_LMALTNAME
+unsetenv_var __MODULES_LMPREREQ
+setenv_loaded_module [list vmod1/1] [list $mp/vmod1/1]
+setenv_var __MODULES_LMCONFLICT vmod1/1&vmod1
+
+set ans [list]
+lappend ans [list set __MODULES_LMALTNAME vmod2/1&vmod2/default&vmod2]
+lappend ans [list set __MODULES_LMCONFLICT vmod1/1&vmod1:vmod2/1&vmod2:vmod3/1&vmod3]
+lappend ans [list set __MODULES_LMPREREQ vmod3/1&vmod2/2|vmod2]
+lappend ans [list set _LMFILES_ $mp/vmod1/1:$mp/vmod2/1:$mp/vmod3/1]
+lappend ans [list set LOADEDMODULES vmod1/1:vmod2/1:vmod3/1]
+lappend ans [list set __MODULES_LMTAG vmod2/1&auto-loaded]
+#FIXME: as requirement is satisfied in the end, there should not be an error
+lappend ans [list ERR]
+testouterr_cmd sh {load --auto vmod3/1} $ans $tserr
+
+
 #
 #  Cleanup
 #