diff --git a/bootstrap/bootstrap b/bootstrap/bootstrap
index a6977534..d7821a01 100755
--- a/bootstrap/bootstrap
+++ b/bootstrap/bootstrap
@@ -31,8 +31,8 @@ def main():
     # three lumps needed - see bootstrap/README.txt
     lumps = [
         (b"PLAYPAL", read()),
-        (b"TEXTURE1", struct.pack("i", 0)),  # empty texture1
-        (b"PNAMES", struct.pack("i8s", 1, b"")),
+        (b"TEXTURE1", struct.pack("<i", 0)),  # empty texture1
+        (b"PNAMES", struct.pack("<i8s", 1, b"")),
     ]  # single pname
 
     # calculate wad directory (lump offsets etc.)
@@ -43,7 +43,7 @@ def main():
         pos += len(data)
 
     # write wad header
-    write(struct.pack("4sii", b"IWAD", len(waddir), pos))
+    write(struct.pack("<4sii", b"IWAD", len(waddir), pos))
 
     # write lump contents
     for name, data in lumps:
@@ -51,7 +51,7 @@ def main():
 
     # write wad directory
     for i in waddir:
-        write(struct.pack("ii8s", *i))
+        write(struct.pack("<ii8s", *i))
 
 
 if __name__ == "__main__":
diff --git a/lumps/colormap/colormap b/lumps/colormap/colormap
index bc12934e..ed1dc499 100755
--- a/lumps/colormap/colormap
+++ b/lumps/colormap/colormap
@@ -49,7 +49,7 @@ def read_palette(filename):
     for i in range(256):
         data = f.read(3)
 
-        color = struct.unpack("BBB", data)
+        color = struct.unpack("<BBB", data)
         colors.append(color)
 
     return colors
@@ -159,7 +159,7 @@ def solid_color_list(color):
 def output_colormap(colormap):
     """Output the given palette to stdout."""
     for c in colormap:
-        x = struct.pack("B", c)
+        x = struct.pack("<B", c)
         os.write(sys.stdout.fileno(), x)
 
 
diff --git a/lumps/genmidi/a2i_file.py b/lumps/genmidi/a2i_file.py
index e8e67426..2630451e 100644
--- a/lumps/genmidi/a2i_file.py
+++ b/lumps/genmidi/a2i_file.py
@@ -23,7 +23,7 @@ class BitReader:
                 "Reached end of decompress stream "
                 + "(%i bytes)" % len(self.data)
             )
-        result, = struct.unpack("B", self.data[self.index : self.index + 1])
+        result, = struct.unpack("<B", self.data[self.index : self.index + 1])
         self.index += 1
         return result
 
@@ -155,7 +155,7 @@ def decompress(data, data_len):
 
         # print "len: %i" % len(result)
 
-    return struct.pack("%iB" % len(result), *result)
+    return struct.pack("<%iB" % len(result), *result)
 
 
 FIELDS = [
@@ -187,13 +187,13 @@ def decode_type_9(data):
 
     for i in range(len(FIELDS)):
         instr_data[FIELDS[i]], = struct.unpack(
-            "B", decompressed_data[i : i + 1]
+            "<B", decompressed_data[i : i + 1]
         )
 
     # Decode instrument name
 
     ps = decompressed_data[14:]
-    instr_name, = struct.unpack("%ip" % len(ps), ps)
+    instr_name, = struct.unpack("<%ip" % len(ps), ps)
     instr_data["name"] = instr_name.decode("ascii")
 
     return instr_data
diff --git a/lumps/genmidi/genmidi.py b/lumps/genmidi/genmidi.py
index 19f579c7..d89f8117 100644
--- a/lumps/genmidi/genmidi.py
+++ b/lumps/genmidi/genmidi.py
@@ -97,14 +97,14 @@ def encode_instrument_names(instruments):
 
     for instrument in instruments:
         instr_name = instrument.voice1["name"].encode("ascii")
-        result.append(struct.pack("32s", instr_name))
+        result.append(struct.pack("<32s", instr_name))
 
     return b"".join(result)
 
 
 def write(filename, instruments):
     header = struct.pack(
-        "%is" % len(GENMIDI_HEADER), GENMIDI_HEADER.encode("ascii")
+        "<%is" % len(GENMIDI_HEADER), GENMIDI_HEADER.encode("ascii")
     )
 
     with open(filename, "wb") as f:
diff --git a/lumps/genmidi/sbi_file.py b/lumps/genmidi/sbi_file.py
index e6904e6d..f3f8f190 100644
--- a/lumps/genmidi/sbi_file.py
+++ b/lumps/genmidi/sbi_file.py
@@ -28,7 +28,7 @@ def read(filename):
     with open(filename, "rb") as f:
         data = f.read()
 
-    header, name = struct.unpack("4s32s", data[0:36])
+    header, name = struct.unpack("<4s32s", data[0:36])
     header = header.decode("ascii")
 
     if header != HEADER_VALUE:
@@ -38,20 +38,20 @@ def read(filename):
     result = {"name": name.decode("ascii").rstrip("\0").rstrip()}
 
     for i in range(len(FIELDS)):
-        result[FIELDS[i]], = struct.unpack("B", instr_data[i : i + 1])
+        result[FIELDS[i]], = struct.unpack("<B", instr_data[i : i + 1])
 
     return result
 
 
 def write(filename, data):
     with open(filename, "wb") as f:
-        f.write(struct.pack("4s", HEADER_VALUE.encode("ascii")))
-        f.write(struct.pack("32s", data["name"].encode("ascii")))
+        f.write(struct.pack("<4s", HEADER_VALUE.encode("ascii")))
+        f.write(struct.pack("<32s", data["name"].encode("ascii")))
 
         for field in FIELDS:
-            f.write(struct.pack("B", data[field]))
+            f.write(struct.pack("<B", data[field]))
         for x in range(16 - len(FIELDS)):
-            f.write(struct.pack("B", 0))
+            f.write(struct.pack("<B", 0))
 
 
 if __name__ == "__main__":
diff --git a/lumps/playpal/playpal b/lumps/playpal/playpal
index 2011dbe0..209a4342 100755
--- a/lumps/playpal/playpal
+++ b/lumps/playpal/playpal
@@ -83,7 +83,7 @@ def read_palette(filename):
 
     for i in range(256):
         data = f.read(3)
-        color = struct.unpack("BBB", data)
+        color = struct.unpack("<BBB", data)
 
         colors.append(color)
 
@@ -164,7 +164,7 @@ def output_palette(pal):
     for color in palette:
         color = tuple(map(clamp_pixval, color))
 
-        encoded = struct.pack("BBB", *color)
+        encoded = struct.pack("<BBB", *color)
         os.write(sys.stdout.fileno(), encoded)
 
 
diff --git a/lumps/textures/build-textures b/lumps/textures/build-textures
index ee173640..f86791b6 100755
--- a/lumps/textures/build-textures
+++ b/lumps/textures/build-textures
@@ -274,7 +274,7 @@ def write_pnames_lump(pnames, filename):
     with open(filename, "wb") as out:
         out.write(struct.pack("<l", len(pnames)))
         for pname in pnames:
-            out.write(struct.pack("8s", pname.encode("ascii")))
+            out.write(struct.pack("<8s", pname.encode("ascii")))
 
 
 def usage():