diff --git a/Doc/whatsnew/3.2.rst b/Doc/whatsnew/3.2.rst
index 6f0e407..5059f48 100644
--- a/Doc/whatsnew/3.2.rst
+++ b/Doc/whatsnew/3.2.rst
@@ -368,9 +368,9 @@
 module::
 
    >>> import sysconfig
-   >>> sysconfig.get_config_var('SOABI')    # find the version tag
+   >>> sysconfig.get_config_var('SOABI')       # find the version tag
    'cpython-32mu'
-   >>> sysconfig.get_config_var('SO')       # find the full filename extension
+   >>> sysconfig.get_config_var('EXT_SUFFIX')  # find the full filename extension
    '.cpython-32mu.so'
 
 .. seealso::
diff --git a/Lib/distutils/command/build_ext.py b/Lib/distutils/command/build_ext.py
index b1d951e..1ad0d5f 100644
--- a/Lib/distutils/command/build_ext.py
+++ b/Lib/distutils/command/build_ext.py
@@ -677,10 +677,10 @@
         if os.name == "os2":
             ext_path[len(ext_path) - 1] = ext_path[len(ext_path) - 1][:8]
         # extensions in debug_mode are named 'module_d.pyd' under windows
-        so_ext = get_config_var('SO')
+        ext_suffix = get_config_var('EXT_SUFFIX')
         if os.name == 'nt' and self.debug:
-            return os.path.join(*ext_path) + '_d' + so_ext
-        return os.path.join(*ext_path) + so_ext
+            return os.path.join(*ext_path) + '_d' + ext_suffix
+        return os.path.join(*ext_path) + ext_suffix
 
     def get_export_symbols(self, ext):
         """Return the list of symbols that a shared extension has to
diff --git a/Lib/distutils/sysconfig.py b/Lib/distutils/sysconfig.py
index d125e0b..b73503d 100644
--- a/Lib/distutils/sysconfig.py
+++ b/Lib/distutils/sysconfig.py
@@ -191,9 +191,9 @@
                 _osx_support.customize_compiler(_config_vars)
                 _config_vars['CUSTOMIZED_OSX_COMPILER'] = 'True'
 
-        (cc, cxx, opt, cflags, ccshared, ldshared, so_ext, ar, ar_flags) = \
+        (cc, cxx, opt, cflags, ccshared, ldshared, shlib_suffix, ar, ar_flags) = \
             get_config_vars('CC', 'CXX', 'OPT', 'CFLAGS',
-                            'CCSHARED', 'LDSHARED', 'SO', 'AR', 'ARFLAGS')
+                            'CCSHARED', 'LDSHARED', 'SHLIB_SUFFIX', 'AR', 'ARFLAGS')
 
         newcc = None
         if 'CC' in os.environ:
@@ -232,7 +232,7 @@
             linker_exe=cc,
             archiver=archiver)
 
-        compiler.shared_lib_extension = so_ext
+        compiler.shared_lib_extension = shlib_suffix
 
 
 def get_config_h_filename():
@@ -487,6 +487,7 @@
     g['INCLUDEPY'] = get_python_inc(plat_specific=0)
 
     g['SO'] = '.pyd'
+    g['EXT_SUFFIX'] = '.pyd'
     g['EXE'] = ".exe"
     g['VERSION'] = get_python_version().replace(".", "")
     g['BINDIR'] = os.path.dirname(os.path.abspath(sys.executable))
@@ -506,6 +507,7 @@
     g['INCLUDEPY'] = get_python_inc(plat_specific=0)
 
     g['SO'] = '.pyd'
+    g['EXT_SUFFIX'] = '.pyd'
     g['EXE'] = ".exe"
 
     global _config_vars
diff --git a/Lib/distutils/tests/test_build_ext.py b/Lib/distutils/tests/test_build_ext.py
index 065a6a2..44a9852 100644
--- a/Lib/distutils/tests/test_build_ext.py
+++ b/Lib/distutils/tests/test_build_ext.py
@@ -318,8 +318,8 @@
         finally:
             os.chdir(old_wd)
         self.assertTrue(os.path.exists(so_file))
-        so_ext = sysconfig.get_config_var('SO')
-        self.assertTrue(so_file.endswith(so_ext))
+        ext_suffix = sysconfig.get_config_var('EXT_SUFFIX')
+        self.assertTrue(so_file.endswith(ext_suffix))
         so_dir = os.path.dirname(so_file)
         self.assertEqual(so_dir, other_tmp_dir)
 
@@ -328,7 +328,7 @@
         cmd.run()
         so_file = cmd.get_outputs()[0]
         self.assertTrue(os.path.exists(so_file))
-        self.assertTrue(so_file.endswith(so_ext))
+        self.assertTrue(so_file.endswith(ext_suffix))
         so_dir = os.path.dirname(so_file)
         self.assertEqual(so_dir, cmd.build_lib)
 
@@ -355,7 +355,7 @@
         self.assertEqual(lastdir, 'bar')
 
     def test_ext_fullpath(self):
-        ext = sysconfig.get_config_vars()['SO']
+        ext = sysconfig.get_config_var('EXT_SUFFIX')
         # building lxml.etree inplace
         #etree_c = os.path.join(self.tmp_dir, 'lxml.etree.c')
         #etree_ext = Extension('lxml.etree', [etree_c])
diff --git a/Lib/distutils/tests/test_install.py b/Lib/distutils/tests/test_install.py
index 1bd31e2..b190127 100644
--- a/Lib/distutils/tests/test_install.py
+++ b/Lib/distutils/tests/test_install.py
@@ -23,7 +23,7 @@
 def _make_ext_name(modname):
     if os.name == 'nt' and sys.executable.endswith('_d.exe'):
         modname += '_d'
-    return modname + sysconfig.get_config_var('SO')
+    return modname + sysconfig.get_config_var('EXT_SUFFIX')
 
 
 class InstallTestCase(support.TempdirManager,
diff --git a/Lib/sysconfig.py b/Lib/sysconfig.py
index 71da1db..2f5f740 100644
--- a/Lib/sysconfig.py
+++ b/Lib/sysconfig.py
@@ -437,6 +437,7 @@
     vars['BINLIBDEST'] = get_path('platstdlib')
     vars['INCLUDEPY'] = get_path('include')
     vars['SO'] = '.pyd'
+    vars['EXT_SUFFIX'] = '.pyd'
     vars['EXE'] = '.exe'
     vars['VERSION'] = _PY_VERSION_SHORT_NO_DOT
     vars['BINDIR'] = os.path.dirname(_safe_realpath(sys.executable))
diff --git a/Makefile.pre.in b/Makefile.pre.in
index 50ddd8a..6709f4a 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -125,7 +125,9 @@
 CONFINCLUDEPY=	$(CONFINCLUDEDIR)/python$(LDVERSION)
 
 # Symbols used for using shared libraries
-SO=		@SO@
+SHLIB_SUFFIX=	@SHLIB_SUFFIX@
+EXT_SUFFIX=	@EXT_SUFFIX@
+SO=		$(SHLIB_SUFFIX)
 LDSHARED=	@LDSHARED@ $(PY_LDFLAGS)
 BLDSHARED=	@BLDSHARED@ $(PY_LDFLAGS)
 LDCXXSHARED=	@LDCXXSHARED@
@@ -652,6 +654,11 @@
 		-DSOABI='"$(SOABI)"' \
 		-o $@ $(srcdir)/Python/dynload_shlib.c
 
+Python/dynload_hpux.o: $(srcdir)/Python/dynload_hpux.c Makefile
+	$(CC) -c $(PY_CORE_CFLAGS) \
+		-DSHLIB_EXT='"$(EXT_SUFFIX)"' \
+		-o $@ $(srcdir)/Python/dynload_hpux.c
+
 Python/sysmodule.o: $(srcdir)/Python/sysmodule.c Makefile
 	$(CC) -c $(PY_CORE_CFLAGS) \
 		-DABIFLAGS='"$(ABIFLAGS)"' \
@@ -1186,7 +1193,7 @@
 	done
 	@if test -d $(LIBRARY); then :; else \
 		if test "$(PYTHONFRAMEWORKDIR)" = no-framework; then \
-			if test "$(SO)" = .dll; then \
+			if test "$(SHLIB_SUFFIX)" = .dll; then \
 				$(INSTALL_DATA) $(LDLIBRARY) $(DESTDIR)$(LIBPL) ; \
 			else \
 				$(INSTALL_DATA) $(LIBRARY) $(DESTDIR)$(LIBPL)/$(LIBRARY) ; \
diff --git a/Misc/NEWS b/Misc/NEWS
index 6378421..d03d35b 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -794,6 +794,10 @@
 Build
 -----
 
+- Issue #16754: Fix the incorrect shared library extension on linux. Introduce
+  two makefile macros SHLIB_SUFFIX and EXT_SUFFIX. SO now has the value of
+  SHLIB_SUFFIX again (as in 2.x and 3.1). The SO macro is removed in 3.4.
+
 - Issue #5033: Fix building of the sqlite3 extension module when the
   SQLite library version has "beta" in it. Patch by Andreas Pelme.
 
diff --git a/Misc/python-config.in b/Misc/python-config.in
index bb0b008..ac3a2c7 100644
--- a/Misc/python-config.in
+++ b/Misc/python-config.in
@@ -57,7 +57,7 @@
         print(' '.join(libs))
 
     elif opt == '--extension-suffix':
-        print(sysconfig.get_config_var('SO'))
+        print(sysconfig.get_config_var('EXT_SUFFIX'))
 
     elif opt == '--abiflags':
         print(sys.abiflags)
diff --git a/configure b/configure
index b881602..fa8d518 100755
--- a/configure
+++ b/configure
@@ -625,6 +625,7 @@
 ac_subst_vars='LTLIBOBJS
 SRCDIRS
 THREADHEADERS
+EXT_SUFFIX
 SOABI
 LIBC
 LIBM
@@ -652,7 +653,7 @@
 BLDSHARED
 LDCXXSHARED
 LDSHARED
-SO
+SHLIB_SUFFIX
 LIBTOOL_CRUFT
 OTHER_LIBTOOL_OPT
 UNIVERSAL_ARCH_FLAGS
@@ -8392,6 +8393,25 @@
 
 
 
+# SHLIB_SUFFIX is the extension of shared libraries `(including the dot!)
+# -- usually .so, .sl on HP-UX, .dll on Cygwin
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking the extension of shared libraries" >&5
+$as_echo_n "checking the extension of shared libraries... " >&6; }
+if test -z "$SHLIB_SUFFIX"; then
+	case $ac_sys_system in
+	hp*|HP*)
+		case `uname -m` in
+			ia64) SHLIB_SUFFIX=.so;;
+	  		*)    SHLIB_SUFFIX=.sl;;
+		esac
+		;;
+	CYGWIN*)   SHLIB_SUFFIX=.dll;;
+	*)	   SHLIB_SUFFIX=.so;;
+	esac
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $SHLIB_SUFFIX" >&5
+$as_echo "$SHLIB_SUFFIX" >&6; }
+
 # LDSHARED is the ld *command* used to create shared library
 # -- "cc -G" on SunOS 5.x, "ld -shared" on IRIX 5
 # (Shared libraries in this instance are shared modules to be loaded into
@@ -13685,51 +13705,20 @@
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $SOABI" >&5
 $as_echo "$SOABI" >&6; }
 
+
+case $ac_sys_system in
+    Linux*|GNU*)
+	EXT_SUFFIX=.${SOABI}${SHLIB_SUFFIX};;
+    *)
+	EXT_SUFFIX=${SHLIB_SUFFIX};;
+esac
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking LDVERSION" >&5
 $as_echo_n "checking LDVERSION... " >&6; }
 LDVERSION='$(VERSION)$(ABIFLAGS)'
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $LDVERSION" >&5
 $as_echo "$LDVERSION" >&6; }
 
-# SO is the extension of shared libraries `(including the dot!)
-# -- usually .so, .sl on HP-UX, .dll on Cygwin
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking SO" >&5
-$as_echo_n "checking SO... " >&6; }
-if test -z "$SO"
-then
-	case $ac_sys_system in
-	hp*|HP*)
-		case `uname -m` in
-			ia64) SO=.so;;
-	  		*)    SO=.sl;;
-		esac
-		;;
-	CYGWIN*)   SO=.dll;;
-	Linux*|GNU*)
-		   SO=.${SOABI}.so;;
-	*)	   SO=.so;;
-	esac
-else
-	# this might also be a termcap variable, see #610332
-	echo
-	echo '====================================================================='
-	echo '+                                                                   +'
-	echo '+ WARNING: You have set SO in your environment.                     +'
-	echo '+ Do you really mean to change the extension for shared libraries?  +'
-	echo '+ Continuing in 10 seconds to let you to ponder.                    +'
-	echo '+                                                                   +'
-	echo '====================================================================='
-	sleep 10
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $SO" >&5
-$as_echo "$SO" >&6; }
-
-
-cat >>confdefs.h <<_ACEOF
-#define SHLIB_EXT "$SO"
-_ACEOF
-
-
 # Check whether right shifting a negative integer extends the sign bit
 # or fills with zeros (like the Cray J90, according to Tim Peters).
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether right shift extends the sign bit" >&5
diff --git a/configure.ac b/configure.ac
index b555f27..8cf0e92 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1896,13 +1896,30 @@
 esac
 
 # Set info about shared libraries.
-AC_SUBST(SO)
+AC_SUBST(SHLIB_SUFFIX)
 AC_SUBST(LDSHARED)
 AC_SUBST(LDCXXSHARED)
 AC_SUBST(BLDSHARED)
 AC_SUBST(CCSHARED)
 AC_SUBST(LINKFORSHARED)
 
+# SHLIB_SUFFIX is the extension of shared libraries `(including the dot!)
+# -- usually .so, .sl on HP-UX, .dll on Cygwin
+AC_MSG_CHECKING(the extension of shared libraries)
+if test -z "$SHLIB_SUFFIX"; then
+	case $ac_sys_system in
+	hp*|HP*)
+		case `uname -m` in
+			ia64) SHLIB_SUFFIX=.so;;
+	  		*)    SHLIB_SUFFIX=.sl;;
+		esac
+		;;
+	CYGWIN*)   SHLIB_SUFFIX=.dll;;
+	*)	   SHLIB_SUFFIX=.so;;
+	esac
+fi
+AC_MSG_RESULT($SHLIB_SUFFIX)
+
 # LDSHARED is the ld *command* used to create shared library
 # -- "cc -G" on SunOS 5.x, "ld -shared" on IRIX 5
 # (Shared libraries in this instance are shared modules to be loaded into
@@ -3925,43 +3942,18 @@
 SOABI='cpython-'`echo $VERSION | tr -d .`${ABIFLAGS}
 AC_MSG_RESULT($SOABI)
 
+AC_SUBST(EXT_SUFFIX)
+case $ac_sys_system in
+    Linux*|GNU*)
+	EXT_SUFFIX=.${SOABI}${SHLIB_SUFFIX};;
+    *)
+	EXT_SUFFIX=${SHLIB_SUFFIX};;
+esac
+
 AC_MSG_CHECKING(LDVERSION)
 LDVERSION='$(VERSION)$(ABIFLAGS)'
 AC_MSG_RESULT($LDVERSION)
 
-# SO is the extension of shared libraries `(including the dot!)
-# -- usually .so, .sl on HP-UX, .dll on Cygwin
-AC_MSG_CHECKING(SO)
-if test -z "$SO"
-then
-	case $ac_sys_system in
-	hp*|HP*)
-		case `uname -m` in
-			ia64) SO=.so;;
-	  		*)    SO=.sl;;
-		esac
-		;;
-	CYGWIN*)   SO=.dll;;
-	Linux*|GNU*)
-		   SO=.${SOABI}.so;;
-	*)	   SO=.so;;
-	esac
-else
-	# this might also be a termcap variable, see #610332
-	echo
-	echo '====================================================================='
-	echo '+                                                                   +'
-	echo '+ WARNING: You have set SO in your environment.                     +'
-	echo '+ Do you really mean to change the extension for shared libraries?  +'
-	echo '+ Continuing in 10 seconds to let you to ponder.                    +'
-	echo '+                                                                   +'
-	echo '====================================================================='
-	sleep 10
-fi
-AC_MSG_RESULT($SO)
-
-AC_DEFINE_UNQUOTED(SHLIB_EXT, "$SO", [Define this to be extension of shared libraries (including the dot!).])
-
 # Check whether right shifting a negative integer extends the sign bit
 # or fills with zeros (like the Cray J90, according to Tim Peters).
 AC_MSG_CHECKING(whether right shift extends the sign bit)
diff --git a/setup.py b/setup.py
index 7b7e03e..d4183d4 100644
--- a/setup.py
+++ b/setup.py
@@ -169,13 +169,7 @@
     def build_extensions(self):
 
         # Detect which modules should be compiled
-        old_so = self.compiler.shared_lib_extension
-        # Workaround PEP 3149 stuff
-        self.compiler.shared_lib_extension = os.environ.get("SO", ".so")
-        try:
-            missing = self.detect_modules()
-        finally:
-            self.compiler.shared_lib_extension = old_so
+        missing = self.detect_modules()
 
         # Remove modules that are present on the disabled list
         extensions = [ext for ext in self.extensions
@@ -2055,7 +2049,8 @@
     # mode 644 unless they are a shared library in which case they will get
     # mode 755. All installed directories will get mode 755.
 
-    so_ext = sysconfig.get_config_var("SO")
+    # this is works for EXT_SUFFIX too, which ends with SHLIB_SUFFIX
+    shlib_suffix = sysconfig.get_config_var("SHLIB_SUFFIX")
 
     def install(self):
         outfiles = install_lib.install(self)
@@ -2070,7 +2065,7 @@
         for filename in files:
             if os.path.islink(filename): continue
             mode = defaultMode
-            if filename.endswith(self.so_ext): mode = sharedLibMode
+            if filename.endswith(self.shlib_suffix): mode = sharedLibMode
             log.info("changing mode of %s to %o", filename, mode)
             if not self.dry_run: os.chmod(filename, mode)