diff --git a/debian/lenny/dependencies/tqt3/debian/rules b/debian/lenny/dependencies/tqt3/debian/rules
index 047a93868..2b4eaf3ae 100755
--- a/debian/lenny/dependencies/tqt3/debian/rules
+++ b/debian/lenny/dependencies/tqt3/debian/rules
@@ -15,6 +15,10 @@ DEB_HOST_ARCH		?= $(shell dpkg-architecture -qDEB_HOST_ARCH)
 DEB_HOST_ARCH_CPU	?= $(shell dpkg-architecture -qDEB_HOST_ARCH_CPU)
 DEB_HOST_MULTIARCH	?= $(shell dpkg-architecture -qDEB_HOST_MULTIARCH)
 
+# Honour "parallel=N" option of DEB_BUILD_OPTIONS.  Comment out to
+# never build in parallel, regardless of DEB_BUILD_OPTIONS.
+DEB_BUILD_PARALLEL = true
+
 ifeq ($(DEB_HOST_ARCH_OS),hurd)
 	PLATFORM_ARG = hurd-g++
 else #hurd
diff --git a/debian/squeeze/dependencies/tqt3/debian/rules b/debian/squeeze/dependencies/tqt3/debian/rules
index 047a93868..2b4eaf3ae 100755
--- a/debian/squeeze/dependencies/tqt3/debian/rules
+++ b/debian/squeeze/dependencies/tqt3/debian/rules
@@ -15,6 +15,10 @@ DEB_HOST_ARCH		?= $(shell dpkg-architecture -qDEB_HOST_ARCH)
 DEB_HOST_ARCH_CPU	?= $(shell dpkg-architecture -qDEB_HOST_ARCH_CPU)
 DEB_HOST_MULTIARCH	?= $(shell dpkg-architecture -qDEB_HOST_MULTIARCH)
 
+# Honour "parallel=N" option of DEB_BUILD_OPTIONS.  Comment out to
+# never build in parallel, regardless of DEB_BUILD_OPTIONS.
+DEB_BUILD_PARALLEL = true
+
 ifeq ($(DEB_HOST_ARCH_OS),hurd)
 	PLATFORM_ARG = hurd-g++
 else #hurd
diff --git a/ubuntu/maverick/dependencies/tqt3/debian/rules b/ubuntu/maverick/dependencies/tqt3/debian/rules
index 047a93868..2b4eaf3ae 100755
--- a/ubuntu/maverick/dependencies/tqt3/debian/rules
+++ b/ubuntu/maverick/dependencies/tqt3/debian/rules
@@ -15,6 +15,10 @@ DEB_HOST_ARCH		?= $(shell dpkg-architecture -qDEB_HOST_ARCH)
 DEB_HOST_ARCH_CPU	?= $(shell dpkg-architecture -qDEB_HOST_ARCH_CPU)
 DEB_HOST_MULTIARCH	?= $(shell dpkg-architecture -qDEB_HOST_MULTIARCH)
 
+# Honour "parallel=N" option of DEB_BUILD_OPTIONS.  Comment out to
+# never build in parallel, regardless of DEB_BUILD_OPTIONS.
+DEB_BUILD_PARALLEL = true
+
 ifeq ($(DEB_HOST_ARCH_OS),hurd)
 	PLATFORM_ARG = hurd-g++
 else #hurd