diff --git a/make-includes/standard_rules.make b/make-includes/standard_rules.make
index 2536c26..f386bf0 100755
--- a/make-includes/standard_rules.make
+++ b/make-includes/standard_rules.make
@@ -101,16 +101,16 @@
 # PNG from TIFF, JPEG, PICT (normal image)
 # Note: PNG prerequisites are dealt with further down.
 #
-convert_normal = `$(CONVERT) "$(1)" "$(2)"`
+convert_normal = $(CONVERT) "$(1)" "$(2)"
 
 %.png %-print.png %-web.png: %.tif
-	$(call convert-normal,$<,$(IMGDIR)/$@)
+	$(call convert_normal,$<,$(IMGDIR)/$@)
 
 %.png %-print.png %-web.png: %.jpg
-	$(call convert-normal,$<,$(IMGDIR)/$@)
+	$(call convert_normal,$<,$(IMGDIR)/$@)
 
 %.png %-print.png %-web.png: %.pict
-	$(call convert-normal,$<,$(IMGDIR)/$@)
+	$(call convert_normal,$<,$(IMGDIR)/$@)
 #
 # PNG from PNG, TIFF, JPEG, PICT (slide background)
 #
@@ -122,7 +122,7 @@
 # Includes both blurred and unblurred versions, use as required.
 #
 # Unblurred:
-convert_bg = `$(CONVERT) "$(1)" -threshold "-1" -depth 16 - | $(COMPOSITE) -dissolve 33% "$(1)" - "$(2)"`
+convert_bg = $(CONVERT) "$(1)" -threshold "-1" -depth 16 - | $(COMPOSITE) -dissolve 33% "$(1)" - "$(2)"
 
 %-BG.png: %.tif
 	$(call convert_bg,$<,$(IMGDIR)/$@)
@@ -137,7 +137,7 @@
 	$(call convert_bg,$<,$(IMGDIR)/$@)
 #
 # Blurred:
-convert_bg_blur = `$(CONVERT) -blur 0.5 "$(1)" "$(2)"; $(CONVERT) "$(2)" -threshold "-1" -depth 16 - | $(COMPOSITE) -dissolve 33% "$(2)" - "$(3)"; rm -f "$(2)"`
+convert_bg_blur = $(CONVERT) -blur 0.5 "$(1)" "$(2)"; $(CONVERT) "$(2)" -threshold "-1" -depth 16 - | $(COMPOSITE) -dissolve 33% "$(2)" - "$(3)"; rm -f "$(2)"
 
 %-BG-blur.png: %.tif
 	$(call convert_bg_blur,$<,$(IMGDIR)/$*-tmp.png,$(IMGDIR)/$@)