diff --git a/gcc-preinclude.h b/gcc-preinclude.h
index ffd31a914e..33a351f9fd 100644
--- a/gcc-preinclude.h
+++ b/gcc-preinclude.h
@@ -2,6 +2,8 @@
 // See: http://www.win.tue.nl/~aeb/linux/misc/gcc-semibug.html
 //      https://rjpower9000.wordpress.com/2012/04/09/fun-with-shared-libraries-version-glibc_2-14-not-found/
 
+#define _GNU_SOURCE 1
+
 #include <features.h>
 
 #ifndef __ASSEMBLER__
diff --git a/src/core/memory.c b/src/core/memory.c
index d47dc3795f..e6d95350ba 100644
--- a/src/core/memory.c
+++ b/src/core/memory.c
@@ -9,7 +9,7 @@
 // virtual addresses (remove the tag bits) and to test addresses for
 // validity (check the tag bits).
 
-#define _GNU_SOURCE
+#define _GNU_SOURCE 1
 
 #include <assert.h>
 #include <fcntl.h>
diff --git a/src/lib/traceprof/traceprof.c b/src/lib/traceprof/traceprof.c
index dc43f40a45..553e527977 100644
--- a/src/lib/traceprof/traceprof.c
+++ b/src/lib/traceprof/traceprof.c
@@ -1,6 +1,6 @@
 // Location where the next instruction pointer value will be stored.
 
-#define _GNU_SOURCE
+#define _GNU_SOURCE 1
 
 #include <assert.h>
 #include <stdio.h>