diff --git a/include/fmt/format.h b/include/fmt/format.h
index c2ec2e5c..4996aba4 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -116,7 +116,8 @@
 #endif
 
 #if FMT_USE_USER_DEFINED_LITERALS && \
-    (FMT_GCC_VERSION >= 600 || FMT_CLANG_VERSION >= 304)
+    (FMT_GCC_VERSION >= 600 || \
+    (defined(FMT_CLANG_VERSION) && FMT_CLANG_VERSION >= 304))
 # define FMT_UDL_TEMPLATE 1
 #else
 # define FMT_UDL_TEMPLATE 0