diff --git a/FML/COLASolver/src/Simulation.h b/FML/COLASolver/src/Simulation.h
index 15216923..4625771b 100644
--- a/FML/COLASolver/src/Simulation.h
+++ b/FML/COLASolver/src/Simulation.h
@@ -791,7 +791,7 @@ void NBodySimulation<NDIM, T>::init() {
         const int col_k = 0;
         const int col_pofk = 1;
         std::vector<int> cols_to_keep{col_k, col_pofk};
-        const int nheaderlines = 1;
+        const int nheaderlines = -1; // skip header comments
         auto pofkdata = FML::FILEUTILS::read_regular_ascii(ic_input_filename, ncols, cols_to_keep, nheaderlines);
 
         karr.resize(pofkdata.size());
@@ -838,7 +838,7 @@ void NBodySimulation<NDIM, T>::init() {
         const int col_k = 0;
         const int col_tofk = 1;
         std::vector<int> cols_to_keep{col_k, col_tofk};
-        const int nheaderlines = 1;
+        const int nheaderlines = -1; // skip header comments
         auto tofkdata = FML::FILEUTILS::read_regular_ascii(ic_input_filename, ncols, cols_to_keep, nheaderlines);
 
         karr.resize(tofkdata.size());
diff --git a/FML/FileUtils/FileUtils.cpp b/FML/FileUtils/FileUtils.cpp
index f8996d6d..4d8773d8 100644
--- a/FML/FileUtils/FileUtils.cpp
+++ b/FML/FileUtils/FileUtils.cpp
@@ -11,6 +11,7 @@ namespace FML {
         // Read a regular ascii files with nskip header lines and containing ncol collums
         // nestimated_lines is the amount we allocate for originally. Reallocated if file is larger
         // Not perfect for realy large files due to all the allocations we have to do
+        // If nskip is negative, header lines starting with # are skipped
         DVector2D read_regular_ascii(std::string filename,
                                      int ncols,
                                      std::vector<int> cols_to_keep,
@@ -18,7 +19,7 @@ namespace FML {
                                      size_t nestimated_lines) {
 
             // Sanity check
-            assert(cols_to_keep.size() > 0 and nskip >= 0 and ncols > 0);
+            assert(cols_to_keep.size() > 0 and ncols > 0);
             for (auto & i : cols_to_keep)
                 assert(i < ncols and i >= 0);
 
@@ -37,8 +38,8 @@ namespace FML {
             DVector newline(ntokeep);
             DVector temp(ncols);
 
-            // Read and skip header lines
-            for (int i = 0; i < nskip; i++) {
+            // Read and skip header lines (fixed number or all lines starting with #)
+            for (int i = 0; i < nskip || (nskip < 0 && fp && fp.peek() == '#'); i++) {
                 std::string line;
                 std::getline(fp, line);
 #ifdef DEBUG_READASCII