diff --git a/src/PJ_bertin1953.c b/src/PJ_bertin1953.c
index 19aa4d53b7..5ec7ac9a7c 100644
--- a/src/PJ_bertin1953.c
+++ b/src/PJ_bertin1953.c
@@ -31,23 +31,24 @@ static XY s_forward (LP lp, PJ *P) {
     XY xy = {0.0,0.0};
     struct pj_opaque *Q = P->opaque;
 
-    // Projection constants
+    /* Projection constants */
     double fu = 1.4, k = 12., w = 1.68;
 
-    // Aliases
+    /* Aliases */
     double lambda = lp.lam, phi = lp.phi;
     
-    // Variable
+    /* Variable */
     double d;
 
-    // Apply rotation
+    /* Apply rotation */
 	lambda += Q->deltaLambda;
 
-    double cosphi = cos(phi),
-      x = cos(lambda) * cosphi,
-      y = sin(lambda) * cosphi,
-      z = sin(phi),
-      z0 = z * Q->cosDeltaPhi + x * Q->sinDeltaPhi;
+    double cosphi, x, y, z, z0;
+    cosphi = cos(phi);
+    x = cos(lambda) * cosphi;
+    y = sin(lambda) * cosphi;
+    z = sin(phi);
+    z0 = z * Q->cosDeltaPhi + x * Q->sinDeltaPhi;
     lambda = atan2(y * Q->cosDeltaGamma - z0 * Q->sinDeltaGamma,
        x * Q->cosDeltaPhi - z * Q->sinDeltaPhi);
     z0 = z0 * Q->cosDeltaGamma + y * Q->sinDeltaGamma;
@@ -55,20 +56,20 @@ static XY s_forward (LP lp, PJ *P) {
 
     lambda = adjlon(lambda);
 
-    // Adjust pre-projection
+    /* Adjust pre-projection */
     if (lambda + phi < -fu) {
-      double u = (lambda - phi + 1.6) * (lambda + phi + fu) / 8.;
-      lambda += u;
-      phi -= 0.8 * u * sin(phi + M_PI / 2.);
+      d = (lambda - phi + 1.6) * (lambda + phi + fu) / 8.;
+      lambda += d;
+      phi -= 0.8 * d * sin(phi + M_PI / 2.);
     }
 
-    // Project with Hammer (1.68,2)
+    /* Project with Hammer (1.68,2) */
     cosphi = cos(phi);
     d = sqrt(2./(1. + cosphi * cos(lambda / 2.)));
     xy.x = w * d * cosphi * sin(lambda / 2.);
     xy.y = d * sin(phi);
 
-    // Adjust post-projection
+    /* Adjust post-projection */
     d = (1. - cos(lambda * phi)) / k;
     if (xy.y < 0.) {
       xy.x *= 1. + d;
@@ -87,12 +88,14 @@ PJ *PROJECTION(bertin1953) {
         return pj_default_destructor (P, ENOMEM);
     P->opaque = Q;
 
-    // force +lon_0 = -16.5
-    double deltaLambda = P->lam0 -16.5 / 180. * M_PI;
+    double deltaLambda, deltaPhi, deltaGamma;
+
+    /* force +lon_0 = -16.5 */
+    deltaLambda = P->lam0 -16.5 / 180. * M_PI;
 
-    // force +lat_0=-42
-    double deltaPhi = -42. / 180. * M_PI,
-      deltaGamma = 0.  / 180. * M_PI;
+    /* force +lat_0=-42 */
+    deltaPhi = -42. / 180. * M_PI;
+    deltaGamma = 0. / 180. * M_PI;
 
     Q->deltaLambda = deltaLambda;
     Q->cosDeltaPhi = cos(deltaPhi);
@@ -102,7 +105,7 @@ PJ *PROJECTION(bertin1953) {
 
     P->es = 0.;
     P->fwd = s_forward;
-    // P->inv = s_inverse;
+    /* P->inv = s_inverse; */
 
     return P;
 }