diff --git a/cpuid/x86.cpp b/cpuid/x86.cpp
index 92663cd2..fb13dd51 100644
--- a/cpuid/x86.cpp
+++ b/cpuid/x86.cpp
@@ -161,10 +161,12 @@ cruft::cpu::operator<< (std::ostream &os, const x86 &val)
 
     fmt::print (
         os,
-        "{ name: { vendor: '{}', product: '{}' }"
-        ", cores: { logical: {}, physical: {}, hyper_threading: {} }"
-        ", simd: { sse: {}, sse2: {}, sse3: {}, ssse3: {}, sse41: {}, sse42: {}, avx: {} }"
-        " }",
+        FMT_STRING(
+            "{{ name: {{ vendor: '{}', product: '{}' }}"
+            ", cores: {{ logical: {}, physical: {}, hyper_threading: {} }}"
+            ", simd: {{ sse: {}, sse2: {}, sse3: {}, ssse3: {}, sse41: {}, sse42: {}, avx: {} }}"
+            " }}"
+        ),
         to_string (val.vendor_name),
         to_string (val.product_name),
         val.cores.logical,