diff --git a/configure.in b/configure.in
index f9d6c75de0..9bb085a621 100644
--- a/configure.in
+++ b/configure.in
@@ -18,7 +18,7 @@ AC_DIVERT_PUSH(AC_DIVERSION_NOTICE)dnl
 esyscmd([sed "s/^/# /" COPYRIGHT])dnl
 AC_DIVERT_POP()dnl
 
-AC_REVISION($Revision: 1.315 $)
+AC_REVISION($Revision: 1.316 $)
 
 AC_INIT(lib/dns/name.c)
 AC_PREREQ(2.13)
@@ -1424,9 +1424,18 @@ found_rt_iflist
 #
 # Check for some other useful functions that are not ever-present.
 #
-AC_CHECK_FUNC(strsep,
-	[ISC_PLATFORM_NEEDSTRSEP="#undef ISC_PLATFORM_NEEDSTRSEP"],
-	[ISC_PLATFORM_NEEDSTRSEP="#define ISC_PLATFORM_NEEDSTRSEP 1"])
+
+# We test for strsep() using AC_TRY_LINK instead of AC_CHECK_FUNC
+# because AIX 4.3.3 with patches for bos.adt.include to version 4.3.3.77
+# reportedly defines strsep() without declaring it in <string.h> when
+# -D_LINUX_SOURCE_COMPAT is not defined [RT #2190], and
+# AC_CHECK_FUNC() incorrectly succeeds because it declares
+# the function itself.
+AC_MSG_CHECKING(for correctly declared strsep())
+AC_TRY_LINK([#include <string.h>], [char *sp; char *foo = strsep(&sp, ".");],
+	[AC_MSG_RESULT(yes); ISC_PLATFORM_NEEDSTRSEP="#undef ISC_PLATFORM_NEEDSTRSEP"],
+	[AC_MSG_RESULT(no); ISC_PLATFORM_NEEDSTRSEP="#define ISC_PLATFORM_NEEDSTRSEP 1"])
+
 AC_CHECK_FUNC(vsnprintf,
 	[ISC_PLATFORM_NEEDVSNPRINTF="#undef ISC_PLATFORM_NEEDVSNPRINTF"],
 	[ISC_EXTRA_OBJS="$ISC_EXTRA_OBJS print.$O"