diff --git a/runtime/vm/os_linux.cc b/runtime/vm/os_linux.cc
index 14e0f617b57..8d983952ee1 100644
--- a/runtime/vm/os_linux.cc
+++ b/runtime/vm/os_linux.cc
@@ -44,6 +44,11 @@ namespace dart {
 #define ElfW(Type) Elf32_##Type
 #endif
 
+// Missing from older versions of <elf.h>.
+#if !defined(EM_RISCV)
+#define EM_RISCV 243
+#endif
+
 #ifndef PRODUCT
 
 DEFINE_FLAG(bool,