diff --git a/sys/cddl/dev/dtrace/amd64/dtrace_isa.c b/sys/cddl/dev/dtrace/amd64/dtrace_isa.c
index 07a1b0a7ae8a..e05932d77e3c 100644
--- a/sys/cddl/dev/dtrace/amd64/dtrace_isa.c
+++ b/sys/cddl/dev/dtrace/amd64/dtrace_isa.c
@@ -440,7 +440,7 @@ dtrace_getarg(int arg, int aframes)
 	}
 
 	arg -= (inreg + 1);
-	stack = (uintptr_t *)fp + 2;
+	stack = (uintptr_t *)&fp[1];
 
 load:
 	DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
diff --git a/sys/x86/include/stack.h b/sys/x86/include/stack.h
index 8e45b82b06d0..3489e42c5802 100644
--- a/sys/x86/include/stack.h
+++ b/sys/x86/include/stack.h
@@ -45,7 +45,6 @@ struct i386_frame {
 struct amd64_frame {
 	struct amd64_frame	*f_frame;
 	u_long			f_retaddr;
-	u_long			f_arg0;
 };
 
 struct i386_frame {