Thanks for the replies. Like I mentioned before, if I remove the VERSION parameter, the problem goes away, but I lose the version number which can be seen in the file properties. This numbering is not part of any WinAPI - it's just static metadata in the file.

I did notice the following two parameters in the docs which sounded promising, but setting them didn't seem to change the results. I wonder - is the lib template for qmake hard-coded, or is it defined in a file somewhere?

TARGET_x
This variable specifies the target's extension with a major version number. The value of this variable is typically handled by qmake or qmake.conf and rarely needs to be modified.

TARGET_x.y.z
This variable specifies the target's extension with version number. The value of this variable is typically handled by qmake or qmake.conf and rarely needs to be modified.