--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1115,6 +1115,20 @@ IF(LINUX_FEDORA_28 OR LINUX_FEDORA_34 OR
   ENDIF()
 ENDIF()
 
+# riscv64 needs -latomic for std::atomic<bool>, as RISC-V doesn't provide byte
+# atomics. But because of --as-needed and because I don't know how to use
+# cmake, let's use -pthread instead.
+CHECK_C_SOURCE_COMPILES(
+"#ifndef __riscv
+#error Not RISC-V
+#endif
+int main() {}"
+IS_RISCV
+)
+IF(IS_RISCV)
+  STRING_APPEND(CMAKE_CXX_LINK_FLAGS " -pthread")
+ENDIF()
+
 IF(LINK_RANDOMIZE)
   STRING_APPEND(CMAKE_C_FLAGS   " -ffunction-sections -fdata-sections")
   STRING_APPEND(CMAKE_CXX_FLAGS " -ffunction-sections -fdata-sections")