diff --git a/sys/amd64/amd64/bios.c b/sys/amd64/amd64/bios.c
index 541bd3f7afd5..687a7920f288 100644
--- a/sys/amd64/amd64/bios.c
+++ b/sys/amd64/amd64/bios.c
@@ -262,7 +262,7 @@ set_bios_selectors(struct bios_segments *seg, int flags)
     union descriptor *p_gdt;
 
 #ifdef SMP
-    p_gdt = &gdt[cpuid];
+    p_gdt = &gdt[cpuid * NGDT];
 #else
     p_gdt = gdt;
 #endif
diff --git a/sys/i386/i386/bios.c b/sys/i386/i386/bios.c
index 541bd3f7afd5..687a7920f288 100644
--- a/sys/i386/i386/bios.c
+++ b/sys/i386/i386/bios.c
@@ -262,7 +262,7 @@ set_bios_selectors(struct bios_segments *seg, int flags)
     union descriptor *p_gdt;
 
 #ifdef SMP
-    p_gdt = &gdt[cpuid];
+    p_gdt = &gdt[cpuid * NGDT];
 #else
     p_gdt = gdt;
 #endif