diff --git a/build/jam/ArchitectureRules b/build/jam/ArchitectureRules
index 7a0cd9a273..346b90127b 100644
--- a/build/jam/ArchitectureRules
+++ b/build/jam/ArchitectureRules
@@ -498,7 +498,7 @@ rule ArchitectureSetupWarnings architecture
 	rule EnableWerror dirTokens : scope {
 		# Clang gives way more warnings than GCC, so that code won't compile
 		# -Werror when using Clang.
-		if $(HAIKU_CC_IS_CLANG_$(architecture)) = 0 {
+		if $(HAIKU_CC_IS_CLANG_$(architecture)) != 1 {
 			SetConfigVar WARNINGS : HAIKU_TOP $(dirTokens) : treatAsErrors
 				: $(scope) ;
 		}