diff --git a/libvips/colour/sRGB2HSV.c b/libvips/colour/sRGB2HSV.c
index 6b30ca0a..0e8057ab 100644
--- a/libvips/colour/sRGB2HSV.c
+++ b/libvips/colour/sRGB2HSV.c
@@ -78,7 +78,7 @@ vips_sRGB2HSV_line( VipsColour *colour, VipsPel *out, VipsPel **in, int width )
 				c_max = p[0];
 				c_min = p[2];
 				secondary_diff = p[1] - p[2];
-				wrap_around_hue = 0f;
+				wrap_around_hue = 0.0f;
 			} else {
 				c_max = p[1];
 				c_min = VIPS_MIN(p[2], p[0]);