diff -up digikam-5.7.0/core/libs/rawengine/libraw/internal/dcraw_common.cpp.glibc digikam-5.7.0/core/libs/rawengine/libraw/internal/dcraw_common.cpp
--- digikam-5.7.0/core/libs/rawengine/libraw/internal/dcraw_common.cpp.glibc	2017-12-18 16:27:31.961652324 -0600
+++ digikam-5.7.0/core/libs/rawengine/libraw/internal/dcraw_common.cpp	2017-12-18 17:08:01.934366587 -0600
@@ -6790,7 +6790,7 @@ void CLASS PentaxLensInfo (unsigned id,
 		if (table_buf[iLensData+9] &&
 			(fabs(imgdata.lens.makernotes.CurFocal) < 0.1f))
 		  imgdata.lens.makernotes.CurFocal =
-			10*(table_buf[iLensData+9]>>2) * powf64(4, (table_buf[iLensData+9] & 0x03)-2);
+			10*(table_buf[iLensData+9]>>2) * powf64(4.0f, (float)((table_buf[iLensData+9] & 0x03)-2));
 		if (table_buf[iLensData+10] & 0xf0)
 		  imgdata.lens.makernotes.MaxAp4CurFocal =
 			powf64(2.0f, (float)((table_buf[iLensData+10] & 0xf0) >>4)/4.0f);