diff --git a/cmd/wuffs-c/release.go b/cmd/wuffs-c/release.go
index b68bc5d..4eb0162 100644
--- a/cmd/wuffs-c/release.go
+++ b/cmd/wuffs-c/release.go
@@ -170,10 +170,12 @@
 #if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wmissing-field-initializers"
-#pragma GCC diagnostic ignored "-Wold-style-cast"
 #pragma GCC diagnostic ignored "-Wunreachable-code"
 #pragma GCC diagnostic ignored "-Wunused-function"
 #pragma GCC diagnostic ignored "-Wunused-parameter"
+#if defined(__cplusplus)
+#pragma GCC diagnostic ignored "-Wold-style-cast"
+#endif
 #endif
 
 `
diff --git a/release/c/wuffs-unsupported-snapshot.c b/release/c/wuffs-unsupported-snapshot.c
index b1791a0..b8945bb 100644
--- a/release/c/wuffs-unsupported-snapshot.c
+++ b/release/c/wuffs-unsupported-snapshot.c
@@ -13,10 +13,12 @@
 #if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wmissing-field-initializers"
-#pragma GCC diagnostic ignored "-Wold-style-cast"
 #pragma GCC diagnostic ignored "-Wunreachable-code"
 #pragma GCC diagnostic ignored "-Wunused-function"
 #pragma GCC diagnostic ignored "-Wunused-parameter"
+#if defined(__cplusplus)
+#pragma GCC diagnostic ignored "-Wold-style-cast"
+#endif
 #endif
 
 // Copyright 2017 The Wuffs Authors.