diff --git a/src/builtin.c b/src/builtin.c
index fb7513ceaf..d4869387c4 100644
--- a/src/builtin.c
+++ b/src/builtin.c
@@ -1,6 +1,3 @@
-#ifndef _GNU_SOURCE
-# define _GNU_SOURCE
-#endif
 #ifndef __sun__
 # define _XOPEN_SOURCE
 # define _XOPEN_SOURCE_EXTENDED 1
diff --git a/src/compile.c b/src/compile.c
index 5645fa5f90..4af74ff641 100644
--- a/src/compile.c
+++ b/src/compile.c
@@ -1,6 +1,3 @@
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE // for strdup
-#endif
 #include <assert.h>
 #include <math.h>
 #include <string.h>
diff --git a/src/inject_errors.c b/src/inject_errors.c
index b61a27139d..a9fe9a82d5 100644
--- a/src/inject_errors.c
+++ b/src/inject_errors.c
@@ -1,5 +1,3 @@
-
-#define _GNU_SOURCE /* for RTLD_NEXT */
 #include <assert.h>
 #include <dlfcn.h>
 #include <errno.h>
diff --git a/src/util.c b/src/util.c
index 250bdf75f4..a5c2b61b26 100644
--- a/src/util.c
+++ b/src/util.c
@@ -1,8 +1,3 @@
-
-#ifdef HAVE_MEMMEM
-#define _GNU_SOURCE
-#endif
-
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <assert.h>