diff --git a/tcl/main.tcl.in b/tcl/main.tcl.in
index 87a7f41cb..6dc49355f 100644
--- a/tcl/main.tcl.in
+++ b/tcl/main.tcl.in
@@ -637,7 +637,20 @@ if {[catch {
       rename ::__initStateClockSeconds ::initStateClockSeconds
       rename ::__parseDateTimeArg ::parseDateTimeArg
    }
+   # wrap getFilesInDirectory with in-memory cache to avoid redundant
+   # directory reads within a single modulecmd invocation
+   rename ::getFilesInDirectory ::_getFilesInDirectoryUncached
+   proc getFilesInDirectory {dir fetch_dotversion} {
+      set cachekey $dir:$fetch_dotversion
+      if {[info exists ::g_filesInDirCache($cachekey)]} {
+         return $::g_filesInDirCache($cachekey)
+      }
+      set result [_getFilesInDirectoryUncached $dir $fetch_dotversion]
+      set ::g_filesInDirCache($cachekey) $result
+      return $result
+   }
    ##nagelfar syntax readFile x x? x?
+   ##nagelfar syntax _getFilesInDirectoryUncached x x
    ##nagelfar syntax getFilesInDirectory x x
    ##nagelfar syntax initStateUsergroups
    ##nagelfar syntax initStateUsername
diff --git a/testsuite/modules.90-avail/025-memcache.exp b/testsuite/modules.90-avail/025-memcache.exp
new file mode 100644
index 000000000..fb113987b
--- /dev/null
+++ b/testsuite/modules.90-avail/025-memcache.exp
@@ -0,0 +1,31 @@
+##############################################################################
+#   Modules Revision 3.0
+#   Providing a flexible user environment
+#
+#   Description:  In-memory cache for getFilesInDirectory
+#   Command:      avail
+#   Modulefiles:  loc_rc1, loc_fq
+#
+#   Test that the in-memory directory read cache returns correct results
+#   when the same modulepath is queried multiple times within a single
+#   invocation. The cache wraps getFilesInDirectory so repeated avail
+#   calls on overlapping paths must produce identical results.
+#
+##############################################################################
+
+# test that consecutive avail queries return consistent results
+# first query populates the cache, second should hit it
+set ts2 "$modpath:\nloc_rc1/1.0(foo)\nloc_rc1/2.0"
+testouterr_cmd "sh" "avail -t loc_rc1" "OK" $ts2
+
+# second query on same path exercises the cache
+testouterr_cmd "sh" "avail -t loc_fq" "OK" $ts1
+
+skip_if_quick_mode
+
+# query a different module in the same modulepath
+set ts2 "$modpath:\nloc_rc1/1.0(foo)"
+testouterr_cmd "sh" "avail -t loc_rc1" "OK" $ts2
+
+# unset local variables
+unset ts1 ts2