diff --git a/CMakeLists.txt b/CMakeLists.txt
index c36097a..2fb7276 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -13,7 +13,7 @@ set(CJSON_UTILS_VERSION_SO 1)
 set(PROJECT_VERSION "${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}.${PROJECT_VERSION_PATCH}")
 
 if(("${CMAKE_C_COMPILER_ID}" MATCHES "GNU") OR ("${CMAKE_C_COMPILER_ID}" MATCHES "Clang"))
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -ansi -pedantic -Wall -Wextra -Werror -Wstrict-prototypes -Wwrite-strings")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c89 -pedantic -Wall -Wextra -Werror -Wstrict-prototypes -Wwrite-strings")
 endif()
 
 #variables for pkg-config
diff --git a/Makefile b/Makefile
index 35d7244..59328be 100644
--- a/Makefile
+++ b/Makefile
@@ -20,7 +20,7 @@ INSTALL_LIBRARY_PATH = $(DESTDIR)$(PREFIX)/$(LIBRARY_PATH)
 
 INSTALL ?= cp -a
 
-R_CFLAGS = -fPIC -ansi -pedantic -Wall -Werror -Wstrict-prototypes -Wwrite-strings $(CFLAGS)
+R_CFLAGS = -fPIC -std=c89 -pedantic -Wall -Werror -Wstrict-prototypes -Wwrite-strings $(CFLAGS)
 
 uname := $(shell sh -c 'uname -s 2>/dev/null || echo false')