Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -85,18 +85,18 @@
 CPP="$OBJCPP"
 CPPFLAGS="$CPPFLAGS $OBJCPPFLAGS"
 OBJCFLAGS="$OBJCFLAGS -Wall -fexceptions -fobjc-exceptions -funwind-tables"
 OBJCFLAGS="$OBJCFLAGS -fconstant-string-class=OFConstantString"
 
-AX_CHECK_COMPILER_FLAGS(-std=c11, [
-	OBJCFLAGS="$OBJCFLAGS -std=c11"
-], [
-	AX_CHECK_COMPILER_FLAGS(-std=c1x, [
-		OBJCFLAGS="$OBJCFLAGS -std=c1x"
-	], [
-		AX_CHECK_COMPILER_FLAGS(-std=c99,
-			[OBJCFLAGS="$OBJCFLAGS -std=c99"])
+AX_CHECK_COMPILER_FLAGS(-std=gnu11, [
+	OBJCFLAGS="$OBJCFLAGS -std=gnu11"
+], [
+	AX_CHECK_COMPILER_FLAGS(-std=gnu1x, [
+		OBJCFLAGS="$OBJCFLAGS -std=gnu1x"
+	], [
+		AX_CHECK_COMPILER_FLAGS(-std=gnu99,
+			[OBJCFLAGS="$OBJCFLAGS -std=gnu99"])
 	])
 ])
 
 AX_CHECK_COMPILER_FLAGS(-pipe, [OBJCFLAGS="$OBJCFLAGS -pipe"])
 AX_CHECK_COMPILER_FLAGS(-fno-common, [OBJCFLAGS="$OBJCFLAGS -fno-common"])
@@ -179,24 +179,10 @@
 	AC_SUBST(USE_SRCS_PLUGINS, '${SRCS_PLUGINS}')
 	AC_SUBST(TESTPLUGIN, "plugin")
 	AC_DEFINE(OF_HAVE_PLUGINS, 1, [Whether we have plugin support])
 ])
 
-AC_MSG_CHECKING(whether we need -D_GNU_SOURCE)
-AC_EGREP_CPP(yes, [
-	#include <stdlib.h>
-
-	#if defined(__GLIBC__) || defined(__MINGW32__)
-	yes
-	#endif
-], [
-	CPPFLAGS="-D_GNU_SOURCE $CPPFLAGS"
-	AC_MSG_RESULT(yes)
-], [
-	AC_MSG_RESULT(no)
-])
-
 case "$host_os" in
 	solaris*)
 		CPPFLAGS="-D__EXTENSIONS__ -D_POSIX_PTHREAD_SEMANTICS $CPPFLAGS"
 		;;
 esac

Index: src/OFDate.m
==================================================================
--- src/OFDate.m
+++ src/OFDate.m
@@ -618,11 +618,11 @@
 - (of_time_interval_t)timeIntervalSinceNow
 {
 	struct timeval t;
 	of_time_interval_t seconds;
 
-	OF_ENSURE(!gettimeofday(&t, NULL));
+	OF_ENSURE(gettimeofday(&t, NULL) == 0);
 
 	seconds = t.tv_sec;
 	seconds += (of_time_interval_t)t.tv_usec / 1000000;
 
 	return _seconds - seconds;