diff --git a/audio/moony-lv2/files/patch-CMakeLists.txt b/audio/moony-lv2/files/patch-CMakeLists.txt
index 7b5599112432..bdbc2643446d 100644
--- a/audio/moony-lv2/files/patch-CMakeLists.txt
+++ b/audio/moony-lv2/files/patch-CMakeLists.txt
@@ -1,14 +1,14 @@
 --- CMakeLists.txt.orig	2017-05-16 21:46:21 UTC
 +++ CMakeLists.txt
-@@ -33,6 +33,17 @@ set(CMAKE_C_FLAGS "-Wshadow -Wimplicit-f
+@@ -33,6 +33,17 @@ set(CMAKE_C_FLAGS "-Wshadow -Wimplicit-function-declar
  if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
  	set(CMAKE_MODULE_LINKER_FLAGS "-Wl,-z,defs ${CMAKE_MODULE_LINKER_FLAGS}")
  	set(CMAKE_MODULE_LINKER_FLAGS "-Wl,-z,nodelete ${CMAKE_MODULE_LINKER_FLAGS}")
 +elseif(CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
 +	# see https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=221341
-+	include(CheckFunctionExists)
-+	check_function_exists(clog FreeBSD_CLOG_EXISTS)
-+	check_function_exists(cpow FreeBSD_CPOW_EXISTS)
++	include(CheckLibraryExists)
++	check_library_exists(m clog 'copmlex.h' FreeBSD_CLOG_EXISTS)
++	check_library_exists(m cpow 'complex.h' FreeBSD_CPOW_EXISTS)
 +	if (FreeBSD_CLOG_EXISTS)
 +		set(CMAKE_C_FLAGS "-DFreeBSD_CLOG_EXISTS ${CMAKE_C_FLAGS}")
 +	endif()