diff --git a/src/afterburnerlib.c b/src/afterburnerlib.c
index 5653db9e9a0028e46aae45ab7f8cf65da3d1c63c..b8f7f3548a5dfb921b30d86808fc5a979872e66d 100644
--- a/src/afterburnerlib.c
+++ b/src/afterburnerlib.c
@@ -1050,7 +1050,7 @@ void MakeGeopotHeight(double *geop, double* gt, double *gq, double *ph, int nhor
   double vtmp;
   double zrg;
   double z2log2;
-  double *geopl, *gtl, *gql, *phl;
+  double *restrict geopl, *restrict gtl, *restrict gql, *restrict phl;
 
   z2log2 = 2.0 * log(2.0);
   vtmp   = (C_RV / PlanetRD) - 1.0;