diff --git a/src/common/version.c b/src/common/version.c
index 2f19f0466..2ebb58b0a 100644
--- a/src/common/version.c
+++ b/src/common/version.c
@@ -49,7 +49,46 @@
 #define VER_MAJOR       2U
 #define VER_MINOR       19U
 
-
+/*
+ * Note: until 2.19 the __CC65__ macro was defined as (VER_MAJOR * 0x100) + VER_MINOR * 0x10
+ * which resulted in broken values starting at version 2.16 of the compiler:
+ *
+ * version  __CC65__    identifies as
+ *
+ * 2.0      0x0200      2.0
+ * 2.1      0x0210      2.16
+ * 2.2      0x0220      2.32
+ * 2.3      0x0230      2.48
+ * 2.4      0x0240      2.64
+ * 2.5      0x0250      2.80
+ * 2.6      0x0260      2.96
+ * 2.7      0x0270      2.112
+ * 2.8      0x0280      2.128
+ * 2.9      0x0290      2.144
+ * 2.10     0x02a0      2.160
+ * 2.11     0x02b0      2.176
+ * 2.12     0x02c0      2.192
+ * 2.13     0x02d0      2.208
+ * 2.14     0x02e0      2.224
+ * 2.15     0x02f0      2.240
+ * 2.16     0x0300      3.0
+ * 2.17     0x0310      3.16
+ * 2.18     0x0320      3.32
+ * 2.19     0x0330      3.48
+ * 2.19-git 0x0213      2.19
+ *
+ * to keep damage low(er), we should do the following:
+ *
+ * - bump to 3.1 (skip 3.0) before 2.32
+ * - bump to 4.0 before 3.16
+ *
+ * That way at least each value is unique, and checking compiler version(s) can
+ * still work to some degree, should it really be necessary.
+ *
+ * Some preprocessor kludges can be used to still check for greater or lesser
+ * versions - see the checkversion program in the samples directory.
+ *
+ */
 
 /*****************************************************************************/
 /*                                   Code                                    */
@@ -74,5 +113,8 @@ const char* GetVersionAsString (void)
 unsigned GetVersionAsNumber (void)
 /* Returns the version number as a combined unsigned for use in a #define */
 {
-    return ((VER_MAJOR * 0x100) + (VER_MINOR * 0x10));
+#if VER_MINOR >= 0x100
+#error "VER_MINOR must be smaller than 0x100 - time to bump the major version!"
+#endif
+    return ((VER_MAJOR * 0x100) + VER_MINOR);
 }