diff --git a/Makefile b/Makefile
index 3d6569e..3f1d7ee 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,7 @@ export PGOPTIONS = -c enable_indexonlyscan=off
 endif
 
 pg_config_h := $(shell $(PG_CONFIG) --includedir-server)/pg_config.h
-use_float8_byval := $(shell grep -q 'USE_FLOAT8_BYVAL 1' $(pg_config_h) && echo yes)
+use_float8_byval := $(shell if grep -q 'USE_FLOAT8_BYVAL 1' $(pg_config_h) || grep -q 'SIZEOF_VOID_P 8' $(pg_config_h); then echo yes; fi)
 comma = ,
 
 extension_version = 0