diff --git a/src/build/Common.gmake b/src/build/Common.gmake
index 5eda986841838322800bb97893bc32f9ee626e49..2672d70464f5a7382d574cef1e32e7591bc8974d 100644
--- a/src/build/Common.gmake
+++ b/src/build/Common.gmake
@@ -298,7 +298,7 @@ endif
 
 # PThread-specific flags
 ifeq ($(os),linux)    # Linux
- CFLAGS	+=	-DPOSIX_C_SOURCE=200809L -D_BSD_SOURCE -D_XOPEN_SOURCE=700 -DSPEED_MACROS_ONLY
+ CFLAGS	+=	-DPOSIX_C_SOURCE=200809L -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_XOPEN_SOURCE=700 -DSPEED_MACROS_ONLY
  ifndef THREADS_ACTUALLY_WORK
   CFLAGS    += -D_THREAD_SUID_BROKEN
  endif