diff --git a/artisoptions_christinenonthermal.h b/artisoptions_christinenonthermal.h
index c648cc0db..77c574bcf 100644
--- a/artisoptions_christinenonthermal.h
+++ b/artisoptions_christinenonthermal.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef ARTISOPTIONS_H  // NOLINT(llvm-header-guard)
 #define ARTISOPTIONS_H
 // NOLINTBEGIN(modernize*,misc-unused-parameters)
diff --git a/artisoptions_classic.h b/artisoptions_classic.h
index f937a2687..0e34b81d8 100644
--- a/artisoptions_classic.h
+++ b/artisoptions_classic.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef ARTISOPTIONS_H  // NOLINT(llvm-header-guard)
 #define ARTISOPTIONS_H
 // NOLINTBEGIN(modernize*,misc-unused-parameters)
diff --git a/artisoptions_kilonova_lte.h b/artisoptions_kilonova_lte.h
index f0be2ea4a..3f35ddf43 100644
--- a/artisoptions_kilonova_lte.h
+++ b/artisoptions_kilonova_lte.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef ARTISOPTIONS_H  // NOLINT(llvm-header-guard)
 #define ARTISOPTIONS_H
 // NOLINTBEGIN(modernize*,misc-unused-parameters)
diff --git a/artisoptions_nltenebular.h b/artisoptions_nltenebular.h
index 276b0d4e2..63e607994 100644
--- a/artisoptions_nltenebular.h
+++ b/artisoptions_nltenebular.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef ARTISOPTIONS_H  // NOLINT(llvm-header-guard)
 #define ARTISOPTIONS_H
 // NOLINTBEGIN(modernize*,misc-unused-parameters)
diff --git a/artisoptions_nltewithoutnonthermal.h b/artisoptions_nltewithoutnonthermal.h
index 475bcaa67..4db1817c7 100644
--- a/artisoptions_nltewithoutnonthermal.h
+++ b/artisoptions_nltewithoutnonthermal.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef ARTISOPTIONS_H  // NOLINT(llvm-header-guard)
 #define ARTISOPTIONS_H
 // NOLINTBEGIN(modernize*,misc-unused-parameters)
diff --git a/atomic.h b/atomic.h
index a3b3993ed..b4b0e1a6d 100644
--- a/atomic.h
+++ b/atomic.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef ATOMIC_H
 #define ATOMIC_H
 
diff --git a/constants.h b/constants.h
index a605fca95..a38928eb5 100644
--- a/constants.h
+++ b/constants.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef CONSTANTS_H
 #define CONSTANTS_H
 
diff --git a/decay.h b/decay.h
index 0fbb2d8b9..9e115666b 100644
--- a/decay.h
+++ b/decay.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef DECAY_H
 #define DECAY_H
 
diff --git a/exspec.h b/exspec.h
index 388c8f8ba..1221a4698 100644
--- a/exspec.h
+++ b/exspec.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef EXSPEC_H
 #define EXSPEC_H
 
diff --git a/gammapkt.h b/gammapkt.h
index fbe1f50c1..1f360a241 100644
--- a/gammapkt.h
+++ b/gammapkt.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef GAMMAPKT_H
 #define GAMMAPKT_H
 
diff --git a/globals.h b/globals.h
index e871a9015..db4911180 100644
--- a/globals.h
+++ b/globals.h
@@ -1,4 +1,3 @@
-#pragma once
 #include <limits>
 #ifndef GLOBALS_H
 #define GLOBALS_H
diff --git a/grid.h b/grid.h
index 3e371ecbb..d0bbc8361 100644
--- a/grid.h
+++ b/grid.h
@@ -1,4 +1,3 @@
-#pragma once
 #include <span>
 #ifndef GRIDINIT_H
 #define GRIDINIT_H
diff --git a/input.h b/input.h
index 6807c4ba0..6e53d730c 100644
--- a/input.h
+++ b/input.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef INPUT_H
 #define INPUT_H
 
diff --git a/kpkt.h b/kpkt.h
index 60bbdc588..3c3a35125 100644
--- a/kpkt.h
+++ b/kpkt.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef KPKT_H
 #define KPKT_H
 
diff --git a/ltepop.h b/ltepop.h
index 036605101..14a930846 100644
--- a/ltepop.h
+++ b/ltepop.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef LTEPOP_H
 #define LTEPOP_H
 
diff --git a/macroatom.h b/macroatom.h
index e8cd7f51e..9ebde5e3c 100644
--- a/macroatom.h
+++ b/macroatom.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef MACROATOM_H
 #define MACROATOM_H
 
diff --git a/md5.h b/md5.h
index 0c3b904a8..4b014a789 100644
--- a/md5.h
+++ b/md5.h
@@ -6,7 +6,6 @@
  * Details:    Defines the API for the corresponding MD5 implementation.
  *********************************************************************/
 
-#pragma once
 #ifndef MD5_H
 #define MD5_H
 
diff --git a/nltepop.h b/nltepop.h
index ad0767c3b..f18e155fa 100644
--- a/nltepop.h
+++ b/nltepop.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef NLTEPOP_H
 #define NLTEPOP_H
 
diff --git a/nonthermal.h b/nonthermal.h
index a73c0faff..37933b9dc 100644
--- a/nonthermal.h
+++ b/nonthermal.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef NONTHERMAL_H
 #define NONTHERMAL_H
 
diff --git a/packet.h b/packet.h
index 119cad317..f2dd8ccd7 100644
--- a/packet.h
+++ b/packet.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef PACKET_H
 #define PACKET_H
 
diff --git a/radfield.h b/radfield.h
index a5fa068c3..8a335c1ae 100644
--- a/radfield.h
+++ b/radfield.h
@@ -1,4 +1,3 @@
-#pragma once
 #include <cstddef>
 #ifndef RADFIELD_H
 #define RADFIELD_H
diff --git a/ratecoeff.h b/ratecoeff.h
index b15eb3bbb..c53b5264d 100644
--- a/ratecoeff.h
+++ b/ratecoeff.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef RATECOEFF_H
 #define RATECOEFF_H
 
diff --git a/rpkt.h b/rpkt.h
index 8960a765d..059ea3947 100644
--- a/rpkt.h
+++ b/rpkt.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef RPKT_H
 #define RPKT_H
 
diff --git a/sn3d.h b/sn3d.h
index 59fc16424..6dfb7cce6 100644
--- a/sn3d.h
+++ b/sn3d.h
@@ -1,5 +1,3 @@
-#pragma once
-#include <cstddef>
 #ifndef SN3D_H
 #define SN3D_H
 
@@ -19,6 +17,7 @@
 #include <atomic>
 #include <cassert>
 #include <csignal>
+#include <cstddef>
 #include <cstdio>
 #include <cstring>
 #include <filesystem>
diff --git a/spectrum_lightcurve.h b/spectrum_lightcurve.h
index f753c987d..18f1da7ad 100644
--- a/spectrum_lightcurve.h
+++ b/spectrum_lightcurve.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef SPECTRUM_H
 #define SPECTRUM_H
 
diff --git a/stats.h b/stats.h
index 3b9497d34..effff2caf 100644
--- a/stats.h
+++ b/stats.h
@@ -1,4 +1,3 @@
-#pragma once
 #include <cstddef>
 #ifndef STATS_H
 #define STATS_H
diff --git a/thermalbalance.h b/thermalbalance.h
index d59b369ce..c48997b95 100644
--- a/thermalbalance.h
+++ b/thermalbalance.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef THERMALBALANCE_H
 #define THERMALBALANCE_H
 
diff --git a/update_grid.h b/update_grid.h
index e6e753171..bfe60a2b5 100644
--- a/update_grid.h
+++ b/update_grid.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef UPDATE_GRID_H
 #define UPDATE_GRID_H
 
diff --git a/update_packets.h b/update_packets.h
index da9667e4f..88c40f665 100644
--- a/update_packets.h
+++ b/update_packets.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef UPDATE_PACKETS_H
 #define UPDATE_PACKETS_H
 
diff --git a/vectors.h b/vectors.h
index 18ae136ea..8bee8c776 100644
--- a/vectors.h
+++ b/vectors.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef VECTORS_H
 #define VECTORS_H
 
diff --git a/vpkt.h b/vpkt.h
index a1eb72e43..ad6787e96 100644
--- a/vpkt.h
+++ b/vpkt.h
@@ -1,4 +1,3 @@
-#pragma once
 #ifndef VPKT_H
 #define VPKT_H