diff --git a/NEWS.rst b/NEWS.rst
index 22e706df8..064796da6 100644
--- a/NEWS.rst
+++ b/NEWS.rst
@@ -108,6 +108,9 @@ Modules 5.7.0 (not yet released)
   test suite run is aborted.
 * Correctly match loaded modules specified as requirement with a trailing
   ``/`` character after module name. (fix issue #640)
+* Also consider ``-`` in addition to ``.`` as a version number separator
+  character when selecting a module with the :mconfig:`extended_default`
+  mechanism. (fix issue #619)
 
 
 .. _5.6 release notes:
diff --git a/doc/source/changes.rst b/doc/source/changes.rst
index b4ab6f329..825220fdb 100644
--- a/doc/source/changes.rst
+++ b/doc/source/changes.rst
@@ -764,6 +764,9 @@ Starting version 5.5, characters ``+`` and ``~`` may be part of module name or
 version as long as the string part next to these character is not a valid
 variant name.
 
+Starting version 5.7, character ``-`` is considered a version number separator
+for :mconfig:`extended_default` mechanism.
+
 Environment
 """""""""""
 
diff --git a/doc/source/design/extended-default.rst b/doc/source/design/extended-default.rst
index a93cd53b0..03cbae665 100644
--- a/doc/source/design/extended-default.rst
+++ b/doc/source/design/extended-default.rst
@@ -25,15 +25,16 @@ Specification
   - query soft/1 returns nothing
   - query soft/10.1.2 returns highest among soft/10.1.2.4 soft/10.1.2.3
 
-- In situation where soft/1.1(default) soft/1.2 soft/2.1 soft/2.2
+- In situation where soft/1.1(default) soft/1.2 soft/2.1 soft/2.2 soft/3.4-ad75bc9a
 
   - query soft/1 returns soft/1.1
   - query soft/2 returns soft/2.2
+  - query soft/3.4 returns soft/3.4-ad75bc9a
 
-- Character considered as version number separator: ``.``
+- Characters considered as version number separator: ``.`` and ``-``
 
   - list: ``.`` and ``-``
-  - ``-`` was also considered initially, but cannot determine in all case the highest version specified after this character (may find a hash name, strings like *rc*, *alpha*, *beta*, etc)
+  - ``-`` is considered a version number separator character since version 5.7
   - not possible with ``+`` as it is used by variant specification
 
 - Does not apply to the root part of module name
diff --git a/doc/source/module.rst b/doc/source/module.rst
index 807573a9c..fbde31ccf 100644
--- a/doc/source/module.rst
+++ b/doc/source/module.rst
@@ -3146,8 +3146,9 @@ Constraints can be expressed to refine the selection of module version to:
 Advanced specification of single version or list of versions may benefit from
 the activation of the extended default mechanism (see
 :envvar:`MODULES_EXTENDED_DEFAULT`) to use an abbreviated notation like ``@1``
-to refer to more precise version numbers like ``1.2.3``. Range of versions on
-its side natively handles abbreviated versions.
+to refer to more precise version numbers like ``1.2.3``. Characters ``.`` and
+``-`` are considered version number separator to determine abbreviated
+versions. Range of versions on its side natively handles abbreviated versions.
 
 In order to be specified in a range of versions or compared to a range of
 versions, the version major element should corresponds to a number. For
@@ -5008,9 +5009,9 @@ ENVIRONMENT
 
  If set to ``1``, a specified module version is matched against starting
  portion of existing module versions, where portion is a substring separated
- from the rest of the version string by a ``.`` character. For example
+ from the rest of the version string by ``.`` or ``-`` characters. For example
  specified modules ``mod/1`` and ``mod/1.2`` will match existing modulefile
- ``mod/1.2.3``.
+ ``mod/1.2.3`` and ``mod/2.4`` will match ``mod/2.4-91db5cf2``.
 
  In case multiple modulefiles match the specified module version and a single
  module has to be selected, the explicitly set default version is returned if
@@ -5026,6 +5027,9 @@ ENVIRONMENT
 
     .. versionadded:: 4.4
 
+    .. versionchanged:: 5.7
+       Character ``-`` is also considered a version number separator
+
 .. envvar:: MODULES_FAMILY_<NAME>
 
  Module name minus version that provides for the *name* family in currently
diff --git a/doc/source/modulefile.rst b/doc/source/modulefile.rst
index 39169c8e7..dd587f99a 100644
--- a/doc/source/modulefile.rst
+++ b/doc/source/modulefile.rst
@@ -1949,8 +1949,8 @@ The equivalent :file:`.modulerc` would look like:
 If the extended default mechanism is enabled (see
 :envvar:`MODULES_EXTENDED_DEFAULT` in :ref:`module(1)`) the module version
 specified is matched against starting portion of existing module versions,
-where portion is a substring separated from the rest of version string by a
-``.`` character.
+where portion is a substring separated from the rest of version string by
+``.`` or ``-`` characters.
 
 When the implicit default mechanism and the `Advanced module version
 specifiers`_ are both enabled, a ``default`` and ``latest`` symbolic versions
@@ -2081,7 +2081,9 @@ Advanced specification of single version or list of versions may benefit from
 the activation of the extended default mechanism (see
 :envvar:`MODULES_EXTENDED_DEFAULT` in :ref:`module(1)`) to use an abbreviated
 notation like ``@1`` to refer to more precise version numbers like ``1.2.3``.
-Range of versions on its side natively handles abbreviated versions.
+Characters ``.`` and ``-`` are considered version number separator to
+determine abbreviated versions. Range of versions on its side natively handles
+abbreviated versions.
 
 In order to be specified in a range of versions or compared to a range of
 versions, the version major element should corresponds to a number. For
@@ -2109,6 +2111,9 @@ version will be selected.
    .. versionchanged:: 4.8
       Use of version range is allowed in version list
 
+   .. versionchanged:: 5.7
+      Character ``-`` is also considered a version number separator
+
 Variants
 ^^^^^^^^
 
diff --git a/tcl/modspec.tcl b/tcl/modspec.tcl
index 3325cdb37..97bf7e488 100644
--- a/tcl/modspec.tcl
+++ b/tcl/modspec.tcl
@@ -241,6 +241,10 @@ proc defineDoesModMatchAtDepthProc {contains querydepth test} {
    }
 }
 
+proc extendedDefaultCharGlobMatch {} {
+   return {[-.]*}
+}
+
 # Define procedure to check module version equals pattern. Adapt procedure
 # code whether icase and extended_default are enabled or disabled
 proc defineModVersCmpProc {icase extdfl} {
@@ -270,6 +274,7 @@ proc defineModVersCmpProc {icase extdfl} {
 # alternative definitions of modVersCmp proc
 proc modVersCmpProc {cmpspec versspec modvers test {psuf {}}} {
    set ret 0
+   set echar [extendedDefaultCharGlobMatch]
    switch -- $cmpspec {
       in {
          # check each verspec in list until match
@@ -295,26 +300,27 @@ proc modVersCmpProc {cmpspec versspec modvers test {psuf {}}} {
          # are always extended_default-enabled (as 1.2 includes 1.2.12 for
          # instance) and equal, eqstart and match tests are equivalent
          set ret [expr {[isVersion $modvers] && ([versioncmp $modvers\
-            $versspec] != -1 || [string match $versspec.* $modvers])}]
+            $versspec] != -1 || [string match $versspec$echar $modvers])}]
       }
       le {
          # 'ge' comment also applies here
          set ret [expr {[isVersion $modvers] && ([versioncmp $versspec\
-            $modvers] != -1 || [string match $versspec.* $modvers])}]
+            $modvers] != -1 || [string match $versspec$echar $modvers])}]
       }
       be {
          # 'ge' comment also applies here
          lassign $versspec lovers hivers
          set ret [expr {[isVersion $modvers] && ([versioncmp $modvers\
-            $lovers] != -1 || [string match $lovers.* $modvers]) &&\
+            $lovers] != -1 || [string match $lovers$echar $modvers]) &&\
             ([versioncmp $hivers $modvers] != -1 || [string match\
-            $hivers.* $modvers])}]
+            $hivers$echar $modvers])}]
       }
    }
    return $ret
 }
 proc modVersCmpProcIcase {cmpspec versspec modvers test {psuf {}}} {
    set ret 0
+   set echar [extendedDefaultCharGlobMatch]
    switch -- $cmpspec {
       in {
          foreach inspec $versspec {
@@ -336,24 +342,27 @@ proc modVersCmpProcIcase {cmpspec versspec modvers test {psuf {}}} {
       }
       ge {
          set ret [expr {[isVersion $modvers] && ([versioncmp $modvers\
-            $versspec] != -1 || [string match -nocase $versspec.* $modvers])}]
+            $versspec] != -1 || [string match -nocase $versspec$echar\
+            $modvers])}]
       }
       le {
          set ret [expr {[isVersion $modvers] && ([versioncmp $versspec\
-            $modvers] != -1 || [string match -nocase $versspec.* $modvers])}]
+            $modvers] != -1 || [string match -nocase $versspec$echar\
+            $modvers])}]
       }
       be {
          lassign $versspec lovers hivers
          set ret [expr {[isVersion $modvers] && ([versioncmp $modvers\
-            $lovers] != -1 || [string match $lovers.* $modvers]) &&\
+            $lovers] != -1 || [string match $lovers$echar $modvers]) &&\
             ([versioncmp $hivers $modvers] != -1 || [string match -nocase\
-            $hivers.* $modvers])}]
+            $hivers$echar $modvers])}]
       }
    }
    return $ret
 }
 proc modVersCmpProcExtdfl {cmpspec versspec modvers test {psuf {}}} {
    set ret 0
+   set echar [extendedDefaultCharGlobMatch]
    switch -- $cmpspec {
       in {
          foreach inspec $versspec {
@@ -372,30 +381,31 @@ proc modVersCmpProcExtdfl {cmpspec versspec modvers test {psuf {}}} {
             ##nagelfar ignore Non static subcommand
             set ret [string $test $versspec $modvers]
          }
-         if {!$ret && [string match $versspec.* $modvers]} {
+         if {!$ret && [string match $versspec$echar $modvers]} {
             set ret 1
          }
       }
       ge {
          set ret [expr {[isVersion $modvers] && ([versioncmp $modvers\
-            $versspec] != -1 || [string match $versspec.* $modvers])}]
+            $versspec] != -1 || [string match $versspec$echar $modvers])}]
       }
       le {
          set ret [expr {[isVersion $modvers] && ([versioncmp $versspec\
-            $modvers] != -1 || [string match $versspec.* $modvers])}]
+            $modvers] != -1 || [string match $versspec$echar $modvers])}]
       }
       be {
          lassign $versspec lovers hivers
          set ret [expr {[isVersion $modvers] && ([versioncmp $modvers\
-            $lovers] != -1 || [string match $lovers.* $modvers]) &&\
+            $lovers] != -1 || [string match $lovers$echar $modvers]) &&\
             ([versioncmp $hivers $modvers] != -1 || [string match\
-            $hivers.* $modvers])}]
+            $hivers$echar $modvers])}]
       }
    }
    return $ret
 }
 proc modVersCmpProcIcaseExtdfl {cmpspec versspec modvers test {psuf {}}} {
    set ret 0
+   set echar [extendedDefaultCharGlobMatch]
    switch -- $cmpspec {
       in {
          foreach inspec $versspec {
@@ -414,24 +424,26 @@ proc modVersCmpProcIcaseExtdfl {cmpspec versspec modvers test {psuf {}}} {
             ##nagelfar ignore Non static subcommand
             set ret [string $test -nocase $versspec $modvers]
          }
-         if {!$ret && [string match -nocase $versspec.* $modvers]} {
+         if {!$ret && [string match -nocase $versspec$echar $modvers]} {
             set ret 1
          }
       }
       ge {
          set ret [expr {[isVersion $modvers] && ([versioncmp $modvers\
-            $versspec] != -1 || [string match -nocase $versspec.* $modvers])}]
+            $versspec] != -1 || [string match -nocase $versspec$echar\
+            $modvers])}]
       }
       le {
          set ret [expr {[isVersion $modvers] && ([versioncmp $versspec\
-            $modvers] != -1 || [string match -nocase $versspec.* $modvers])}]
+            $modvers] != -1 || [string match -nocase $versspec$echar\
+            $modvers])}]
       }
       be {
          lassign $versspec lovers hivers
          set ret [expr {[isVersion $modvers] && ([versioncmp $modvers\
-            $lovers] != -1 || [string match $lovers.* $modvers]) &&\
+            $lovers] != -1 || [string match $lovers$echar $modvers]) &&\
             ([versioncmp $hivers $modvers] != -1 || [string match -nocase\
-            $hivers.* $modvers])}]
+            $hivers$echar $modvers])}]
       }
    }
    return $ret
@@ -536,10 +548,11 @@ proc defineModEqStaticProc {icase extdfl modspec} {
             append procbody "
                if {!\$ret && \[string first / \$pmod\] != -1} {
                   if {\$test eq {match}} {
-                     set pmodextdfl \$pmod.*
+                     set pmodextdfl \$pmod
                   } else {
-                     set pmodextdfl {$pmodescglob.*}
+                     set pmodextdfl {$pmodescglob}
                   }
+                  append pmodextdfl \[extendedDefaultCharGlobMatch\]
                   set ret \[string match $nocasearg\$pmodextdfl \$mod\]
                }"
          }
@@ -958,10 +971,11 @@ proc modEqProcExtdfl {pattern mod {test equal} {trspec 1} {ismodlo 0} {vrcmp\
       # try the extended default match if not root module and not eqspec test
       if {![info exists eqspec] && !$ret && [string first / $pmod] != -1} {
          if {$test eq {match}} {
-            set pmodextdfl $pmod.*
+            set pmodextdfl $pmod
          } else {
-            set pmodextdfl $pmodescglob.*
+            set pmodextdfl $pmodescglob
          }
+         append pmodextdfl [extendedDefaultCharGlobMatch]
          set ret [string match $pmodextdfl $mod]
          if {!$ret && [llength $altlist]} {
             foreach alt $altlist {
@@ -1107,10 +1121,11 @@ proc modEqProcIcaseExtdfl {pattern mod {test equal} {trspec 1} {ismodlo 0}\
       # try the extended default match if not root module and not eqspec test
       if {![info exists eqspec] && !$ret && [string first / $pmod] != -1} {
          if {$test eq {match}} {
-            set pmodextdfl $pmod.*
+            set pmodextdfl $pmod
          } else {
-            set pmodextdfl $pmodescglob.*
+            set pmodextdfl $pmodescglob
          }
+         append pmodextdfl [extendedDefaultCharGlobMatch]
          set ret [string match -nocase $pmodextdfl $mod]
          if {!$ret && [llength $altlist]} {
             foreach alt $altlist {
diff --git a/testsuite/modules.70-maint/260-extended_default.exp b/testsuite/modules.70-maint/260-extended_default.exp
index 69aabe73a..c2037475b 100644
--- a/testsuite/modules.70-maint/260-extended_default.exp
+++ b/testsuite/modules.70-maint/260-extended_default.exp
@@ -81,7 +81,7 @@ setenv_var MODULES_EXTENDED_DEFAULT 1
 
 # test over different kind of module versions
 array set exactmatch [list extdfl/1.1.0 1 extdfl/2.0 1]
-foreach {query match} [list extdfl/1 extdfl/1.3.1 extdfl/1.0 extdfl/1.0.2 extdfl/1.0.0 ERR extdfl/1.1 extdfl/1.1.0-beta extdfl/1.1.0 extdfl/1.1.0 extdfl/1.2 extdfl/1.2.10 extdfl/1.3 extdfl/1.3.1 extdfl/1.4 extdfl/1.4.5 ext*l/1.4 ERR ext?fl/1.4 ERR extdfl/2 extdfl/2.0.1 extdfl/2.0 extdfl/2.0 extdfl2/3.0 extdfl2/3.0.15 extdfl2/3 extdfl2/3.10.2 extdfl2/3.1 extdfl2/3.1.7 extdfl2/3.9 extdfl2/3.9.2 extdfl2/3.09 extdfl2/3.09.3 extdfl3/1 extdfl3/1.3/4 extdflb ERR extdflb.4 ERR extdflc ERR e.t.fl/1.4 e.t.fl/1.4.5 e??.*/1.4 ERR] {
+foreach {query match} [list extdfl/1 extdfl/1.3.1 extdfl/1.0 extdfl/1.0.2 extdfl/1.0.0 extdfl/1.0.0-beta extdfl/1.1 extdfl/1.1.0-beta extdfl/1.1.0 extdfl/1.1.0 extdfl/1.2 extdfl/1.2.10 extdfl/1.3 extdfl/1.3.1 extdfl/1.4 extdfl/1.4.5 ext*l/1.4 ERR ext?fl/1.4 ERR extdfl/2 extdfl/2.0.1 extdfl/2.0 extdfl/2.0 extdfl2/3.0 extdfl2/3.0.15 extdfl2/3 extdfl2/3.10.2 extdfl2/3.1 extdfl2/3.1.7 extdfl2/3.9 extdfl2/3.9.2 extdfl2/3.09 extdfl2/3.09.3 extdfl3/1 extdfl3/1.3/4 extdflb ERR extdflb.4 ERR extdflc ERR e.t.fl/1.4 e.t.fl/1.4.5 e??.*/1.4 ERR] {
     if {$match eq {ERR}} {
         set ans ERR
         set tserr $err_path'$query'