diff --git a/test/cfg/runtests.sh b/test/cfg/runtests.sh
index 51dff0d53..5294671c3 100755
--- a/test/cfg/runtests.sh
+++ b/test/cfg/runtests.sh
@@ -16,7 +16,7 @@ CPPCHECK_OPT='--check-library --enable=information --enable=style --error-exitco
 CXX=g++
 CXX_OPT='-fsyntax-only -std=c++0x'
 CC=gcc
-CC_OPT='-Wno-nonnull -fsyntax-only'
+CC_OPT='-Wno-nonnull -Wno-implicit-function-declaration -fsyntax-only'
 
 # posix.c
 ${CC} ${CC_OPT} ${DIR}posix.c