diff --git a/cty/value_ops.go b/cty/value_ops.go
index 8c37535c..8c42e795 100644
--- a/cty/value_ops.go
+++ b/cty/value_ops.go
@@ -1283,9 +1283,7 @@ func (val Value) AsBigFloat() *big.Float {
 	}
 
 	// Copy the float so that callers can't mutate our internal state
-	ret := *(val.v.(*big.Float))
-
-	return &ret
+	return new(big.Float).Copy(val.v.(*big.Float))
 }
 
 // AsValueSlice returns a []cty.Value representation of a non-null, non-unknown
diff --git a/cty/value_ops_test.go b/cty/value_ops_test.go
index 4261a35d..6ae36e63 100644
--- a/cty/value_ops_test.go
+++ b/cty/value_ops_test.go
@@ -3432,3 +3432,18 @@ func TestHasWhollyKnownType(t *testing.T) {
 		})
 	}
 }
+
+func TestFloatCopy(t *testing.T) {
+	// ensure manipulating floats does not modify the cty.Value
+	v := NumberFloatVal(1.9)
+	vString := v.GoString()
+
+	// do something that will modify the internal big.Float mantissa
+	f := v.AsBigFloat()
+	i, _ := f.Int(nil)
+	f.SetInt(i)
+
+	if vString != v.GoString() {
+		t.Fatalf("original value changed from %s to %#v", vString, v)
+	}
+}