diff --git a/.Rbuildignore b/.Rbuildignore
index 73609e8..30b9100 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -34,3 +34,4 @@ dparser.*\.(zip|pdf)$
 ^_pkgdown\.yml$
 ^docs$
 ^pkgdown$
+^revdep$
diff --git a/.gitignore b/.gitignore
index 00efe07..b8deac0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,3 +15,4 @@ inst/doc
 /src/dparser/.*
 *.so
 docs
+revdep/
diff --git a/CRAN-SUBMISSION b/CRAN-SUBMISSION
index 11263e0..e212d36 100644
--- a/CRAN-SUBMISSION
+++ b/CRAN-SUBMISSION
@@ -1,3 +1,3 @@
-Version: 1.3.1-12
-Date: 2024-09-17 21:41:28 UTC
-SHA: 02f72d4ec4bef5c2fb321730e07cfc1ae372231b
+Version: 1.3.1-13
+Date: 2024-10-22 18:41:22 UTC
+SHA: dc90eb4f4927f916970d2e282e79f55e725e823d
diff --git a/NEWS.md b/NEWS.md
index 0962ee8..0b28bbb 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,7 +1,7 @@
 # dparser 1.3.1-13
 
-- R version specific code for calling R within C to match version
-  specific requirements (#19)
+- Changed `Makevars` header order, strict options so that `dparser`
+  will compile on older versions of R (#19, #20, #22)
 
 # dparser 1.3.1-12
 
diff --git a/cran-comments.md b/cran-comments.md
index 936adba..f40cf76 100644
--- a/cran-comments.md
+++ b/cran-comments.md
@@ -1,7 +1,3 @@
 # dparser
 
-- This fixes the `Strict` issues flagged by CRAN.
-
-- This also adds a non-abi interface to dparser from C.  This means
-  this can be updated without updating all of the
-  'rxode2'/'nlmixr2est' ecosystem in the future.
+- This fix allows older version of `R` to compile
diff --git a/src/Makevars b/src/Makevars
index 0c58b58..639fb27 100644
--- a/src/Makevars
+++ b/src/Makevars
@@ -1,3 +1 @@
-PKG_CFLAGS  = -DUSE_FREELISTS -DTRACK_PNODES -DSTRICT_R_HEADERS=1
-SOURCES_C = parse.c scan.c dsymtab.c util.c mkdparse.c write_tables.c grammar.g.c gram.c lex.c lr.c version.c read_binary.c dparser.c mkdparser.c rdparse.c
-OBJECTS = $(SOURCES_C:.c=.o)
+PKG_CFLAGS  = -DUSE_FREELISTS -DTRACK_PNODES
diff --git a/src/rdparse.c b/src/rdparse.c
index 41aa0aa..21a1382 100644
--- a/src/rdparse.c
+++ b/src/rdparse.c
@@ -1,12 +1,11 @@
-#include "gramgram.h"
-#include "d.h"
-#include "mkdparse.h"
-#include "dparse.h"
-#define R_NO_REMAP
 #include <R.h>
 #include <Rinternals.h>
 #include <R_ext/Rdynload.h>
 #include <Rmath.h>
+#include "gramgram.h"
+#include "d.h"
+#include "mkdparse.h"
+#include "dparse.h"
 extern int d_use_file_name;
 extern char *d_file_name;
 extern int d_use_r_headers;
@@ -27,12 +26,7 @@ void callparsefn(char *name, char *value, int pos, int depth, SEXP fn, SEXP env)
    fn(name = name, value = value, pos = pos, depth = depth)
    */
   SEXP s, t;
-#if R_MAJOR > 4 || (R_MAJOR == 4 && R_MINOR >= 4)
   t = s = PROTECT(LCONS(R_NilValue, Rf_allocList(4)));
-#else
-  t = s = PROTECT(Rf_allocList(5));
-  SET_TYPEOF(s, LANGSXP);
-#endif
   SETCAR(t, fn); t = CDR(t);
   // name = name
   SETCAR(t, Rf_mkString(name));
@@ -57,12 +51,7 @@ int callskipchildrenfn(char *name, char *value, int pos, int depth, SEXP skip_fn
    */
   SEXP s, t;
   int ret;
-#if R_MAJOR > 4 || (R_MAJOR == 4 && R_MINOR >= 4)
   t = s = PROTECT(LCONS(R_NilValue, Rf_allocList(4)));
-#else
-  t = s = PROTECT(Rf_allocList(5));
-  SET_TYPEOF(s, LANGSXP);
-#endif
   SETCAR(t, skip_fn); t = CDR(t);
   // name = name
   SETCAR(t, Rf_mkString(name));