diff --git a/build_release_package.sh b/build_release_package.sh
index 621476c..778a08d 100755
--- a/build_release_package.sh
+++ b/build_release_package.sh
@@ -6,7 +6,7 @@ declare -r releasedir='releases'
 declare -r docdir='doc'
 declare -r mks='mktsimple'
 
-temp="$(grep "${mks}_version =" share/mktsimple/one_to_one_cpp.mk)"
+temp="$(grep "${mks}_version :=" share/mktsimple/one_to_one_cpp.mk)" || { echo "ERROR: No version" >&2; exit 1; }
 release_version="${temp##* }"
 
 echo
@@ -25,7 +25,7 @@ while [[ ("${response}" != 'y') && ("${response}" != 'yes') ]]; do
 done
 
 for x in in_place_cpp.mk out_place_c.mk out_place_cpp.mk out_place.mk; do
-	temp="$(grep "${mks}_version =" share/mktsimple/${x})"
+	temp="$(grep "${mks}_version :=" share/mktsimple/${x})" || { echo "ERROR: No version in ${x}" >&2; exit 1; }
 	release_version_x="${temp##* }"
 	if [[ "${release_version}" != "${release_version_x}" ]]; then
 		echo "ERROR: Version info ${release_version_x} of ${x} does not match!" >&2
diff --git a/share/mktsimple/in_place_cpp.mk b/share/mktsimple/in_place_cpp.mk
index 4708f29..86573c3 100644
--- a/share/mktsimple/in_place_cpp.mk
+++ b/share/mktsimple/in_place_cpp.mk
@@ -1,5 +1,5 @@
 # version
-mktsimple_version = 4.2.1
+mktsimple_version := 4.2.1
 # Prepare the help string if required
 ifneq (,$(findstring help,$(MAKECMDGOALS)))
   define helpstring =
diff --git a/share/mktsimple/one_to_one_cpp.mk b/share/mktsimple/one_to_one_cpp.mk
index d45da45..c4456fc 100644
--- a/share/mktsimple/one_to_one_cpp.mk
+++ b/share/mktsimple/one_to_one_cpp.mk
@@ -1,5 +1,5 @@
 # version
-mktsimple_version = 4.2.1
+mktsimple_version := 4.2.1
 # Prepare the help string if required
 ifneq (,$(findstring help,$(MAKECMDGOALS)))
   define helpstring =
diff --git a/share/mktsimple/out_place.mk b/share/mktsimple/out_place.mk
index 23776f7..8f92892 100644
--- a/share/mktsimple/out_place.mk
+++ b/share/mktsimple/out_place.mk
@@ -1,5 +1,5 @@
 # version
-mktsimple_version = 4.2.1
+mktsimple_version := 4.2.1
 # Prepare the help string if required
 ifneq (,$(findstring help,$(MAKECMDGOALS)))
   define helpstring =
diff --git a/share/mktsimple/out_place_c.mk b/share/mktsimple/out_place_c.mk
index 71d93f2..1e635a9 100644
--- a/share/mktsimple/out_place_c.mk
+++ b/share/mktsimple/out_place_c.mk
@@ -1,5 +1,5 @@
 # version
-mktsimple_version = 4.2.1
+mktsimple_version := 4.2.1
 # Prepare the help string if required
 ifneq (,$(findstring help,$(MAKECMDGOALS)))
   define helpstring =
diff --git a/share/mktsimple/out_place_cpp.mk b/share/mktsimple/out_place_cpp.mk
index 367cba4..65a51d9 100644
--- a/share/mktsimple/out_place_cpp.mk
+++ b/share/mktsimple/out_place_cpp.mk
@@ -1,5 +1,5 @@
 # version
-mktsimple_version = 4.2.1
+mktsimple_version := 4.2.1
 # Prepare the help string if required
 ifneq (,$(findstring help,$(MAKECMDGOALS)))
   define helpstring =