diff --git a/lib/libthr/arch/amd64/include/pthread_md.h b/lib/libthr/arch/amd64/include/pthread_md.h
index 9f6d3a137dc8..0ebea2e3bd24 100644
--- a/lib/libthr/arch/amd64/include/pthread_md.h
+++ b/lib/libthr/arch/amd64/include/pthread_md.h
@@ -71,7 +71,7 @@ struct tcb {
 	u_long __i;						\
 	__asm __volatile("movq %%fs:%1, %0"			\
 	    : "=r" (__i)					\
-	    : "m" (*(u_long *)(__tcb_offset(name))));		\
+	    : "m" (*(volatile u_long *)(__tcb_offset(name))));  \
 	__result = (__tcb_type(name))__i;			\
 								\
 	__result;						\
diff --git a/lib/libthr/arch/i386/include/pthread_md.h b/lib/libthr/arch/i386/include/pthread_md.h
index 5c00cf694d31..c160aa4fb4ad 100644
--- a/lib/libthr/arch/i386/include/pthread_md.h
+++ b/lib/libthr/arch/i386/include/pthread_md.h
@@ -70,7 +70,7 @@ struct tcb {
 	u_int __i;						\
 	__asm __volatile("movl %%gs:%1, %0"			\
 	    : "=r" (__i)					\
-	    : "m" (*(u_int *)(__tcb_offset(name))));		\
+	    : "m" (*(volatile u_int *)(__tcb_offset(name))));	\
 	__result = (__tcb_type(name))__i;			\
 								\
 	__result;						\