diff --git a/configure.in b/configure.in
index 65808aa378eb..b0c6866acb89 100644
--- a/configure.in
+++ b/configure.in
@@ -63,7 +63,7 @@ dnl ========================================================
 GLIB_VERSION=1.2.0
 PERL_VERSION=5.006
 PYTHON_VERSION_MAJOR=2
-PYTHON_VERSION_MINOR=6
+PYTHON_VERSION_MINOR=5
 CAIRO_VERSION=1.10
 PANGO_VERSION=1.14.0
 GTK2_VERSION=2.10.0
@@ -803,7 +803,7 @@ else
     AC_MSG_RESULT([yes])
 fi
 
-MOZ_PATH_PROGS(PYTHON, $PYTHON python2.7 python2.6 python)
+MOZ_PATH_PROGS(PYTHON, $PYTHON python2.7 python2.6 python2.5 python)
 if test -z "$PYTHON"; then
     AC_MSG_ERROR([python was not found in \$PATH])
 fi
@@ -1839,7 +1839,7 @@ case "$host" in
     ;;
 esac
 
-dnl We require version 2.6 or newer of Python to build.
+dnl We require version 2.5 or newer of Python to build.
 AC_MSG_CHECKING([for Python version >= $PYTHON_VERSION_MAJOR.$PYTHON_VERSION_MINOR but not 3.x])
 
 changequote(:)
diff --git a/js/src/configure.in b/js/src/configure.in
index e25f5695d6d4..122910f9cf5b 100644
--- a/js/src/configure.in
+++ b/js/src/configure.in
@@ -55,7 +55,7 @@ NSPR_VERSION=4
 dnl Set the minimum version of toolkit libs used by mozilla
 dnl ========================================================
 PERL_VERSION=5.006
-PYTHON_VERSION=2.6
+PYTHON_VERSION=2.5
 WINDRES_VERSION=2.14.90
 W32API_VERSION=3.14
 
@@ -1405,8 +1405,8 @@ dnl System overrides of the defaults for host
 dnl ========================================================
 case "$host" in
 *mingw*)
-    # we need Python 2.6 on Windows
-    PYTHON_VERSION=2.6
+    # we need Python 2.5 on Windows
+    PYTHON_VERSION=2.5
     if test -n "$_WIN32_MSVC"; then
         HOST_AR=lib
         HOST_AR_FLAGS='-NOLOGO -OUT:"$@"'