diff --git a/src/h5_readFlash.cpp b/src/h5_readFlash.cpp
index 0559a8f..0c78f58 100644
--- a/src/h5_readFlash.cpp
+++ b/src/h5_readFlash.cpp
@@ -179,13 +179,13 @@ void h5_read_flash3_particles (H5File* file,
                         int* totalparticles,
                         int* localnp,
                         int* particle_offset,
-                        float pos1[],
-                        float pos2[],
-                        float pos3[],
-                        float vel1[],
-                        float vel2[],
-                        float vel3[],
-                        int    id[])
+                        float *pos1,
+                        float *pos2,
+                        float *pos3,
+                        float *vel1,
+                        float *vel2,
+                        float *vel3,
+                        int    *id)
 {
 
   herr_t   status;
@@ -339,15 +339,27 @@ void h5_read_flash3_particles (H5File* file,
 
     /* convert buffer into particle struct */
 
+    if (id) {
     for(p=0; p < (pcount); p++) {
       id[p+poffset] = (int)  *(partBuffer+iptag-1+p*numProps);
+    } }
+
+    if (pos1 && pos2 && pos3) {
+    for(p=0; p < (pcount); p++) {
       pos1[p+poffset]  = (float) *(partBuffer+ipx-1+p*numProps);
       pos2[p+poffset]  = (float) *(partBuffer+ipy-1+p*numProps);
       pos3[p+poffset]  = (float) *(partBuffer+ipz-1+p*numProps);
+    }
+    }
+   
+    
+    if (vel1 && vel2 && vel3) {
+    for(p=0; p < (pcount); p++) {
       vel1[p+poffset]  = (float) *(partBuffer+ipvx-1+p*numProps);
       vel2[p+poffset]  = (float) *(partBuffer+ipvy-1+p*numProps);
       vel3[p+poffset]  = (float) *(partBuffer+ipvz-1+p*numProps);
     }
+    }
 
     memspace.close();
     //status = H5Sclose(memspace);
diff --git a/src/h5_readFlash.hpp b/src/h5_readFlash.hpp
index 273ca07..5187232 100644
--- a/src/h5_readFlash.hpp
+++ b/src/h5_readFlash.hpp
@@ -23,13 +23,13 @@ void h5_read_flash3_particles (H5File* file,
                         int* totalparticles,
                         int* localnp,
                         int* particle_offset,
-                        float pos1[],
-                        float pos2[],
-                        float pos3[],
-                        float vel1[],
-                        float vel2[],
-                        float vel3[],
-                        int    id[]);
+                        float *pos1,
+                        float *pos2,
+                        float *pos3,
+                        float *vel1,
+                        float *vel2,
+                        float *vel3,
+                        int    *id);
 
 void h5_read_flash3_header_info(H5File* file,
 				double* time,                   /* simulation time */
diff --git a/src/loadFlash.cpp b/src/loadFlash.cpp
index cc58521..ada498d 100644
--- a/src/loadFlash.cpp
+++ b/src/loadFlash.cpp
@@ -51,29 +51,36 @@ SimuData *CosmoTool::loadFlashMulti(const char *fname, int id, int loadflags)
     data->Omega_Lambda = omegalambda;
 
     // particle data
-    for (int i = 0; i < 3; i++) {
-      data->Pos[i] = new float[data->NumPart];
-      if (data->Pos[i] == 0) {
-	delete data;
+    if (loadflags& NEED_POSITION) {
+      for (int i = 0; i < 3; i++) {
+        data->Pos[i] = new float[data->NumPart];
+        if (data->Pos[i] == 0) {
+	  delete data;
 	return 0;
       }
-    }
+    } }
 
+
+    if (loadflags &NEED_VELOCITY) {
     for (int i = 0; i < 3; i++) {
       data->Vel[i] = new float[data->NumPart];
       if (data->Vel[i] == 0) {
 	delete data;
 	return 0;
       }
-    }
+    } }
  
+    if (loadflags & NEED_GADGET_ID) {
     data->Id = new int[data->NumPart];
     if (data->Id == 0) {
       delete data;
       return 0;
     }
+    }
 
     int offset = 0;
+
+    if (loadflags &(NEED_GADGET_ID|NEED_POSITION|NEED_VELOCITY))
     h5_read_flash3_particles(&file, &npart, &npart, &offset, 
 			     data->Pos[0], data->Pos[1], data->Pos[2], 
 			     data->Vel[0], data->Vel[1], data->Vel[2],
@@ -81,8 +88,8 @@ SimuData *CosmoTool::loadFlashMulti(const char *fname, int id, int loadflags)
 
     for (int i = 0; i < 3; i++) {
       for (int n = 0; n < data->NumPart; n++) {
-	data->Pos[i][n] = data->Pos[i][n] * data->Hubble / kpc2cm;
-	data->Vel[i][n] = data->Vel[i][n] * data->Hubble / km2cm;
+	if (loadflags& NEED_POSITION) data->Pos[i][n] = data->Pos[i][n] * data->Hubble / kpc2cm;
+	if (loadflags&NEED_VELOCITY) data->Vel[i][n] = data->Vel[i][n] * data->Hubble / km2cm;
       }
     }