diff --git a/libguile/guile-snarf.in b/libguile/guile-snarf.in
index 29332e727..d1347037f 100644
--- a/libguile/guile-snarf.in
+++ b/libguile/guile-snarf.in
@@ -10,7 +10,7 @@ test -n "${CPP+set}" || CPP="@CPP@"
 ## We must use a temporary file here, instead of a pipe, because we
 ## need to know if CPP exits with a non-zero status.
 ${CPP} -DSCM_MAGIC_SNARFER "$@" > ${temp} || exit $?
-< ${temp} grep "^SCM__I" | sed -e "s/^SCM__I//" -e 's/SCM__D.*$//g'
+< ${temp} grep "^ *SCM__I" | sed -e "s/^ *SCM__I//" -e 's/SCM__D.*$//g'
 
 ## Apparently, AIX's preprocessor is unhappy if you try to #include an
 ## empty file.