diff --git a/rts/RtsMessages.c b/rts/RtsMessages.c
index d796bcff59a1..3d1f8eff98a4 100644
--- a/rts/RtsMessages.c
+++ b/rts/RtsMessages.c
@@ -50,8 +50,15 @@ barf(const char*s, ...)
 }
 
 // This wrapper is added to call barf from cmm code without varargs.
-// This is a workaround to make clang generate correct calls in wasm target.
-
+// This is a workaround to make clang generate correct calls in wasm
+// target. Wasm does not directly support varargs, so Clang uses a
+// different ABI for varargs calls than normal calls, which no other
+// target does.
+//
+// https://bugs.llvm.org/show_bug.cgi?id=35385
+//
+// TODO: Replace this by allowing Cmm code to indicate where varargs
+// begin and calling `barf` correctly.
 void
 barf_cmm_wrapper(const char*s)
    GNUC3_ATTRIBUTE(__noreturn__);
diff --git a/rts/RtsSymbols.c b/rts/RtsSymbols.c
index ee3135bbc786..f90fdedbae16 100644
--- a/rts/RtsSymbols.c
+++ b/rts/RtsSymbols.c
@@ -1020,7 +1020,7 @@ RTS_LIBFFI_SYMBOLS
 RtsSymbolVal rtsSyms[] = {
 // Wasm doesn't support dynamic linking, and it complains if there is a type mismatch
 // So a simple workaround is not to declare the symbol table.
-#if !defined (wasm32_HOST_ARCH)
+#if !defined (__wasm__)
       RTS_SYMBOLS
       RTS_RET_SYMBOLS
       RTS_POSIX_ONLY_SYMBOLS
@@ -1038,6 +1038,6 @@ RtsSymbolVal rtsSyms[] = {
       // lazy pointers as nonlazy.
       { "dyld_stub_binding_helper", (void*)0xDEADBEEF, false },
 #endif
-#endif /* wasm32_HOST_ARCH */
+#endif /* __wasm__ */
       { 0, 0, false } /* sentinel */
 };