diff --git a/src/assert.h b/src/assert.h
new file mode 100644
index 00000000..a2562f86
--- /dev/null
+++ b/src/assert.h
@@ -0,0 +1,11 @@
+#ifndef ASSERT_H
+#define ASSERT_H
+
+template<bool> struct CompileTimeAssert;
+template<> struct CompileTimeAssert <true> {};
+
+#define STATIC_ASSERT(e) \
+	(CompileTimeAssert <(e) != 0>())
+
+#endif // ASSERT_H
+
diff --git a/src/fitparser.cpp b/src/fitparser.cpp
index 76ba09ed..ff390ba1 100644
--- a/src/fitparser.cpp
+++ b/src/fitparser.cpp
@@ -1,5 +1,6 @@
 #include <cstring>
 #include <QtEndian>
+#include "assert.h"
 #include "fitparser.h"
 
 
@@ -122,6 +123,7 @@ bool FITParser::parseDefinitionMessage(quint8 header)
 	// definition records
 	def->fields = new Field[def->numFields];
 	for (i = 0; i < def->numFields; i++) {
+		STATIC_ASSERT(sizeof(def->fields[i]) == 3);
 		if (!readData((char*)&(def->fields[i]), sizeof(def->fields[i])))
 			return false;
 		_len -= sizeof(def->fields[i]);
@@ -134,6 +136,7 @@ bool FITParser::parseDefinitionMessage(quint8 header)
 
 		def->devFields = new Field[def->numDevFields];
 		for (i = 0; i < def->numDevFields; i++) {
+			STATIC_ASSERT(sizeof(def->devFields[i]) == 3);
 			if (!readData((char*)&(def->devFields[i]),
 			  sizeof(def->devFields[i])))
 				return false;
@@ -302,6 +305,7 @@ bool FITParser::parseHeader()
 	quint16 crc;
 	qint64 len;
 
+	STATIC_ASSERT(sizeof(hdr) == 12);
 	len = _device->read((char*)&hdr, sizeof(hdr));
 	if (len < 0) {
 		_errorString = "I/O error";