diff --git a/src/divesystem_idive.c b/src/divesystem_idive.c
index a23237f..eecfb5a 100644
--- a/src/divesystem_idive.c
+++ b/src/divesystem_idive.c
@@ -52,7 +52,7 @@
 
 #define SZ_ID     0x0A
 #define SZ_RANGE  0x04
-#define SZ_HEADER 0x33
+#define SZ_HEADER 0x32
 #define SZ_SAMPLE 0x2A
 
 #define NSTEPS    1000
diff --git a/src/divesystem_idive_parser.c b/src/divesystem_idive_parser.c
index 4b44879..dc0e5d0 100644
--- a/src/divesystem_idive_parser.c
+++ b/src/divesystem_idive_parser.c
@@ -29,7 +29,7 @@
 
 #define ISINSTANCE(parser) dc_device_isinstance((parser), &divesystem_idive_parser_vtable)
 
-#define SZ_HEADER 0x33
+#define SZ_HEADER 0x32
 #define SZ_SAMPLE 0x2A
 
 #define NGASMIXES 8