diff --git a/math/nauty/Makefile b/math/nauty/Makefile
index c9f73459b98a..2104b3c2bdb7 100644
--- a/math/nauty/Makefile
+++ b/math/nauty/Makefile
@@ -31,6 +31,8 @@ TEST_TARGET=	check
 
 OPTIONS_DEFINE=	DOCS
 
+CFLAGS_powerpc=	-O1
+
 post-build: # build shared libraries: based on how static libraries are created
 	# rebuild .o files with -fPIC
 	@cd ${WRKSRC} ; \