diff --git a/unittests/ASM/X87/FScale-Zero.asm b/unittests/ASM/X87/FScale-Zero.asm
index 4f6423c393..57db659f1d 100644
--- a/unittests/ASM/X87/FScale-Zero.asm
+++ b/unittests/ASM/X87/FScale-Zero.asm
@@ -5,11 +5,14 @@
     "R9": "0",
     "R10": "0",
     "R11": "0",
-    "R12": "0"
+    "R12": "0",
+    "R13": "0x8000000000000000"
   }
 }
 %endif
 
+section .data
+    neg_zero dq 0x8000000000000000   ; -0.0
 
 section .bss
   align 8
@@ -69,4 +72,14 @@ fscale
 fst qword [rel intstor]
 mov r12, [rel intstor]
 
+; tests scaling negative zero
+mov rax, 1048576
+mov qword [rel intstor], rax
+finit
+fild qword [rel intstor]
+fld qword [rel neg_zero]
+fscale
+fst qword [rel intstor]
+mov r13, [rel intstor]
+
 hlt
diff --git a/unittests/ASM/X87_F64/FScale-Zero_F64.asm b/unittests/ASM/X87_F64/FScale-Zero_F64.asm
index 6c178f97db..b3c14301db 100644
--- a/unittests/ASM/X87_F64/FScale-Zero_F64.asm
+++ b/unittests/ASM/X87_F64/FScale-Zero_F64.asm
@@ -11,6 +11,9 @@
 }
 %endif
 
+section .data
+    neg_zero dq 0x8000000000000000   ; -0.0
+
 section .bss
     intstor: resq 1
 
@@ -65,4 +68,14 @@ fscale
 fst qword [rel intstor]
 mov r12, [rel intstor]
 
+; tests scaling negative zero
+mov rax, 1048576
+mov qword [rel intstor], rax
+finit
+fild qword [rel intstor]
+fld qword [rel neg_zero]
+fscale
+fst qword [rel intstor]
+mov r13, [rel intstor]
+
 hlt