diff --git a/config.m4 b/config.m4
index 36c25b5..d29a791 100644
--- a/config.m4
+++ b/config.m4
@@ -11,37 +11,51 @@ if test "$PHP_SYNC" != "no"; then
   SAVED_LIBS="$LIBS"
   LIBS="$LIBS -pthread -lrt"
 
-  AC_TRY_LINK([
-    #include <fcntl.h>
-    #include <sys/mman.h>
-  ], [
-    int fp = shm_open("", O_RDWR | O_CREAT | O_EXCL, 0666);
-  ], [
-    have_shm_open=yes
-    AC_MSG_RESULT([yes])
-
-    PHP_ADD_LIBRARY(rt,,SYNC_SHARED_LIBADD)
-    PHP_SUBST(SYNC_SHARED_LIBADD)
-  ], [
-    AC_MSG_RESULT([no (attempting fallback)])
-
-    dnl # Fallback attempt to link without -lrt.
-    AC_MSG_CHECKING([for shm_open in -pthread])
-
-    LIBS="$SAVED_LIBS -pthread"
-
-    AC_TRY_LINK([
-      #include <fcntl.h>
-      #include <sys/mman.h>
-    ], [
-      int fp = shm_open("", O_RDWR | O_CREAT | O_EXCL, 0666);
-    ], [
+  AC_LINK_IFELSE([
+    AC_LANG_PROGRAM(
+      [[
+        #include <fcntl.h>
+        #include <sys/mman.h>
+      ]],
+      [[
+        int fp = shm_open("", O_RDWR | O_CREAT | O_EXCL, 0666);
+      ]]
+    )],
+    [
       have_shm_open=yes
       AC_MSG_RESULT([yes])
-    ], [
-      AC_MSG_ERROR([shm_open() is not available on this platform])
-    ])
-  ])
+
+      PHP_ADD_LIBRARY(rt,,SYNC_SHARED_LIBADD)
+      PHP_SUBST(SYNC_SHARED_LIBADD)
+    ],
+    [
+      AC_MSG_RESULT([no (attempting fallback)])
+
+      dnl # Fallback attempt to link without -lrt.
+      AC_MSG_CHECKING([for shm_open in -pthread])
+
+      LIBS="$SAVED_LIBS -pthread"
+
+      AC_LINK_IFELSE(
+        [AC_LANG_PROGRAM(
+          [[
+            #include <fcntl.h>
+            #include <sys/mman.h>
+          ]],
+          [[
+            int fp = shm_open("", O_RDWR | O_CREAT | O_EXCL, 0666);
+          ]]
+        )],
+        [
+          have_shm_open=yes
+          AC_MSG_RESULT([yes])
+        ],
+        [
+          AC_MSG_ERROR([shm_open() is not available on this platform])
+        ]
+      )
+    ]
+  )
 
   dnl # Finish defining the basic extension support.
   AC_DEFINE(HAVE_SYNC, 1, [Whether you have synchronization object support])