diff --git a/src/preprocess.c b/src/preprocess.c
index 39aa3c7c..f4152607 100644
--- a/src/preprocess.c
+++ b/src/preprocess.c
@@ -186,10 +186,12 @@ int main(int argc,char **argv)
 
     // Start at beginning of actual kernal data
     int address=0xe4d3;
-    
-    unlink("temp.s");
-    out=fopen("temp.s","w");
-    if (!out) DO_ERROR("Could not write to temp.s");
+
+    char filename[8192];
+    snprintf(filename,8192,"%s/combined.s",directory);
+    unlink(filename);
+    out=fopen(filename,"w");
+    if (!out) DO_ERROR("Could not write to combined.s");
     fprintf(out,"\t.org $%04x\n",address);
     for(int i=0;i<source_count;i++) source_files[i].written=0;
     int written_count;
@@ -203,7 +205,7 @@ int main(int argc,char **argv)
       int next_fixed_routine=-1;
       for(int i=0;i<source_count;i++)
 	if (!source_files[i].written) {
-	  if (source_files[i].address>address)
+	  if (source_files[i].address>=address)
 	    if (source_files[i].address<next_allocated_address) {
 	      next_allocated_address=source_files[i].address;
 	      next_fixed_routine=i;
@@ -225,6 +227,9 @@ int main(int argc,char **argv)
 	  }
 	}
 
+      // Check if done
+      if (next_fixed_routine==-1&&biggest==-1) break;
+      
       fprintf(stderr,"At address $%04x, next allocated address is $%04X. Current space is %d bytes\n",
 	      address,next_allocated_address,space);
       if (biggest>-1)
@@ -233,7 +238,7 @@ int main(int argc,char **argv)
       if (biggest==-1) {
 	// Nothing else fits here.  So write next_fixed_routine
 	fprintf(stderr,"Writing file %s\n",source_files[next_fixed_routine].file);
-	fprintf(out,"; Source file %s\n",source_files[next_fixed_routine].file);
+	fprintf(out,"\n; Source file %s @ $%04X\n",source_files[next_fixed_routine].file,address);
 	fprintf(out,"\t.checkpc $%04x\n\t.advance $%04x,$00\n",
 		next_allocated_address,next_allocated_address);
 	char filename[8192];
@@ -242,7 +247,7 @@ int main(int argc,char **argv)
 	source_files[next_fixed_routine].written=1;
 	address=next_allocated_address+source_files[next_fixed_routine].size;
       } else {
-	fprintf(out,"; Source file %s\n",source_files[biggest].file);
+	fprintf(out,"\n; Source file %s @ $%04x\n",source_files[biggest].file,address);
 	fprintf(stderr,"Writing file %s\n",source_files[biggest].file);
 	char filename[8192];
 	snprintf(filename,8192,"%s/%s",directory,source_files[biggest].file);
@@ -254,6 +259,17 @@ int main(int argc,char **argv)
     fclose(out);
     
     if (retVal) break;
+
+    for(int i=0;i<source_count;i++)
+      if (!source_files[i].written) {
+	fprintf(stderr,"ERROR: Did not write source file '%s'\n",source_files[i].file);
+	DO_ERROR("Did not write all source files.  Did they not fit?");
+      }
+    if (retVal) break;
+
+    fprintf(stderr,"Assembling combined source...\n");
+    snprintf(cmd,8192,"Ophis/bin/ophis %s/combined.s -o %s/OUT.BIN",directory,directory);
+    system(cmd);
     
   } while(0);