diff --git a/m4/knot-check-header.m4 b/m4/knot-check-header.m4
deleted file mode 100644
index 884b98604..000000000
--- a/m4/knot-check-header.m4
+++ /dev/null
@@ -1,49 +0,0 @@
-# KNOT_CHECK_HEADER([prefix], [name], [default], [header], [cflags], [libs])
-# -----------------------------------------------------------------------------
-# Check presence of a library by checking for a header file.
-#
-# - adds --enable-prefix configure flag
-#
-# - if $enable_prefix is yes or auto, checks for the header file
-#
-# - emits an error if $enable_prefix is yes and the header is not present
-#
-# - check can be overridden by setting prefix_CFLAGS and prefix_LIBS
-#   environment variables
-#
-# Output variables: $enable_foo (yes or no), $foo_CFLAGS, and $foo_LIBS
-#
-AC_DEFUN([KNOT_CHECK_HEADER],
-[
-  AC_ARG_ENABLE([$1], AC_HELP_STRING([--enable-$1], [Support for $2 [default $3]]),
-    [enable_][$1][=$enableval], [enable_][$1][=][$3])
-
-  AC_ARG_VAR([$1][_CFLAGS], [C compiler flags for $2, overriding defaults])
-  AC_ARG_VAR([$1][_LIBS], [linker flags for $2, overriding defaults])
-
-  AS_CASE([$enable_][$1],
-    [no], [
-      [$1][_CFLAGS]=
-      [$1][_LIBS]=
-    ],
-    [auto|yes], [
-      AS_IF([test -n "$][$1][_LIBS"], [
-        dnl: skip header check if environment variable is set
-        [enable_][$1][=yes]
-      ],[
-        dnl: check for header
-        AC_CHECK_HEADER([$4], [
-          [enable_][$1]=yes
-          [$1][_CFLAGS]=[$5]
-          [$1][_LIBS]=[$6]
-        ], [
-          AS_IF([test "$enable_][$1][" = auto],
-            [[enable_][$1]=no],
-            [AC_MSG_ERROR([Header file "$4" for $2 not found])]
-          )
-        ])
-      ])
-    ],
-    [AC_MSG_ERROR([Invalid value of --enable-$1])]
-  )
-])