diff --git a/Makefile b/Makefile
index 08f9aa6..29e4a24 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@ DUMP1090_VERSION ?= unknown
 
 CFLAGS ?= -O3 -g
 DUMP1090_CFLAGS := -std=c11 -fno-common -Wall -Wmissing-declarations -Werror -W
-DUMP1090_CPPFLAGS := -I. -DMODES_DUMP1090_VERSION=\"$(DUMP1090_VERSION)\" -DMODES_DUMP1090_VARIANT=\"dump1090-fa\"
+DUMP1090_CPPFLAGS := -I. -D_POSIX_C_SOURCE=200112L -DMODES_DUMP1090_VERSION=\"$(DUMP1090_VERSION)\" -DMODES_DUMP1090_VARIANT=\"dump1090-fa\"
 
 LIBS = -lpthread -lm
 SDR_OBJ = cpu.o sdr.o fifo.o sdr_ifile.o dsp/helpers/tables.o