diff --git a/internal/cgen/base/all-impl.c b/internal/cgen/base/all-impl.c
index f65f3ad..cd54fe6 100644
--- a/internal/cgen/base/all-impl.c
+++ b/internal/cgen/base/all-impl.c
@@ -31,11 +31,14 @@
 #include <stdlib.h>
 #include <string.h>
 
+// Note that Clang also defines __GNUC__.
 #ifdef __cplusplus
 #if __cplusplus >= 201103L
 #include <memory>
-#else
-#warning "Wuffs' C++ code requires -std=c++11 or later"
+#elif defined(__GNUC__)
+#warning "Wuffs' C++ code expects -std=c++11 or later"
+#elif defined(_MSC_VER)
+#pragma message("Wuffs' C++ code expects C++11 or later")
 #endif
 
 extern "C" {
diff --git a/internal/cgen/data/data.go b/internal/cgen/data/data.go
index 1abc974..1242a48 100644
--- a/internal/cgen/data/data.go
+++ b/internal/cgen/data/data.go
@@ -17,7 +17,7 @@
 package data
 
 const BaseAllImplC = "" +
-	"#ifndef WUFFS_INCLUDE_GUARD__BASE\n#define WUFFS_INCLUDE_GUARD__BASE\n\n#if defined(WUFFS_IMPLEMENTATION) && !defined(WUFFS_CONFIG__MODULES)\n#define WUFFS_CONFIG__MODULES\n#define WUFFS_CONFIG__MODULE__BASE\n#endif\n\n// !! WUFFS MONOLITHIC RELEASE DISCARDS EVERYTHING ABOVE.\n\n// !! INSERT base/copyright\n\n#include <stdbool.h>\n#include <stdint.h>\n#include <stdlib.h>\n#include <string.h>\n\n#ifdef __cplusplus\n#if __cplusplus >= 201103L\n#include <memory>\n#else\n#warning \"Wuffs' C++ code requires -std=c++11 or later\"\n#endif\n\nextern \"C\" {\n#endif\n\n// !! INSERT base/all-public.h.\n\n// !! INSERT InterfaceDeclarations.\n\n" +
+	"#ifndef WUFFS_INCLUDE_GUARD__BASE\n#define WUFFS_INCLUDE_GUARD__BASE\n\n#if defined(WUFFS_IMPLEMENTATION) && !defined(WUFFS_CONFIG__MODULES)\n#define WUFFS_CONFIG__MODULES\n#define WUFFS_CONFIG__MODULE__BASE\n#endif\n\n// !! WUFFS MONOLITHIC RELEASE DISCARDS EVERYTHING ABOVE.\n\n// !! INSERT base/copyright\n\n#include <stdbool.h>\n#include <stdint.h>\n#include <stdlib.h>\n#include <string.h>\n\n// Note that Clang also defines __GNUC__.\n#ifdef __cplusplus\n#if __cplusplus >= 201103L\n#include <memory>\n#elif defined(__GNUC__)\n#warning \"Wuffs' C++ code expects -std=c++11 or later\"\n#elif defined(_MSC_VER)\n#pragma message(\"Wuffs' C++ code expects C++11 or later\")\n#endif\n\nextern \"C\" {\n#endif\n\n// !! INSERT base/all-public.h.\n\n// !! INSERT InterfaceDeclarations.\n\n" +
 	"" +
 	"// ----------------\n\n#ifdef __cplusplus\n}  // extern \"C\"\n#endif\n\n// WUFFS C HEADER ENDS HERE.\n#ifdef WUFFS_IMPLEMENTATION\n\n#ifdef __cplusplus\nextern \"C\" {\n#endif\n\n// !! INSERT base/all-private.h.\n\n" +
 	"" +
diff --git a/release/c/wuffs-unsupported-snapshot.c b/release/c/wuffs-unsupported-snapshot.c
index 5fffc3f..580e4eb 100644
--- a/release/c/wuffs-unsupported-snapshot.c
+++ b/release/c/wuffs-unsupported-snapshot.c
@@ -35,11 +35,14 @@
 #include <stdlib.h>
 #include <string.h>
 
+// Note that Clang also defines __GNUC__.
 #ifdef __cplusplus
 #if __cplusplus >= 201103L
 #include <memory>
-#else
-#warning "Wuffs' C++ code requires -std=c++11 or later"
+#elif defined(__GNUC__)
+#warning "Wuffs' C++ code expects -std=c++11 or later"
+#elif defined(_MSC_VER)
+#pragma message("Wuffs' C++ code expects C++11 or later")
 #endif
 
 extern "C" {