diff --git a/README.txt b/README.txt
index ed409d1..0e9d588 100644
--- a/README.txt
+++ b/README.txt
@@ -9,7 +9,7 @@
                                | |                                
                                |_|                                
 
-                                   Version 3
+                                   Version 4
     
 ==============================================================================
 Contact Information
diff --git a/src/Makefile b/src/Makefile
index 8500cf1..7b4d38c 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2,7 +2,7 @@
 # User Options
 #===============================================================================
 
-COMPILER    = intel
+COMPILER    = gnu
 MPI         = no
 OPENMP      = yes
 OPTIMIZE    = yes
diff --git a/src/main.c b/src/main.c
index 677b745..425703f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -2,7 +2,7 @@
 
 int main( int argc, char * argv[] )
 {
-	int version = 3;
+	int version = 4;
 	int mype = 0;
 
 	#ifdef MPI
diff --git a/src/solver.c b/src/solver.c
index 0027db1..4ef3700 100644
--- a/src/solver.c
+++ b/src/solver.c
@@ -902,9 +902,7 @@ int get_pos_interval( float z, float dz)
  * negative direction */
 int get_neg_interval( float z, float dz)
 {
-	// NOTE: a bit of trickery using floors to obtain ceils 
-	int interval = INT_MAX - (int) ( (double) INT_MAX 
-			- (double) ( z / dz ) );
+	int interval = ceil(z/dz);
 	return interval;
 }