diff --git a/sys/arm/include/atomic.h b/sys/arm/include/atomic.h
index d16849873480..02be1bdff555 100644
--- a/sys/arm/include/atomic.h
+++ b/sys/arm/include/atomic.h
@@ -58,9 +58,9 @@
 #define dsb()  __asm __volatile("mcr p15, 0, %0, c7, c10, 4" : : "r" (0) : "memory")
 #define dmb()  __asm __volatile("mcr p15, 0, %0, c7, c10, 5" : : "r" (0) : "memory")
 #else
-#define isb()
-#define dsb()
-#define dmb()
+#define isb()  __asm __volatile("mcr p15, 0, %0, c7, c5, 4" : : "r" (0) : "memory")
+#define dsb()  __asm __volatile("mcr p15, 0, %0, c7, c10, 4" : : "r" (0) : "memory")
+#define dmb()  dsb()
 #endif
 
 #define mb()   dmb()
diff --git a/sys/modules/Makefile b/sys/modules/Makefile
index 15a516373f44..3d1713f69ee1 100644
--- a/sys/modules/Makefile
+++ b/sys/modules/Makefile
@@ -2,6 +2,8 @@
 
 .include <src.opts.mk>
 
+SUBDIR_PARALLEL=
+
 # Modules that include binary-only blobs of microcode should be selectable by
 # MK_SOURCELESS_UCODE option (see below).