diff --git a/qpkg/prereq.c b/qpkg/prereq.c
index f00e9f6..a99518b 100644
--- a/qpkg/prereq.c
+++ b/qpkg/prereq.c
@@ -111,7 +111,7 @@ static int satisfies(const struct pkg *pkg, const struct ref *ref)
 }
 
 
-static int conflicts(const struct pkg *pkg, const struct list *conf)
+static int old_conflicts(const struct pkg *pkg, const struct list *conf)
 {
 	const struct ref *ref;
 
@@ -125,6 +125,21 @@ static int conflicts(const struct pkg *pkg, const struct list *conf)
 }
 
 
+static int new_conflicts(const struct ref *refs)
+{
+	const struct ref *ref;
+	const struct pkg *pkg;
+
+	for (ref = refs; ref; ref = ref->next)
+		for (pkg = ref->pkg->jrb->val; pkg; pkg = pkg->more)
+			if ((pkg->flags & (QPKG_INSTALLED | QPKG_ADDING)) ||
+			    pkg->mark)
+				if (satisfies(pkg, ref))
+					return 1;
+	return 0;
+}
+
+
 /* ----- Recurse through lists and layers of dependencies ------------------ */
 
 
@@ -186,11 +201,13 @@ static void resolve(struct list *next_dep, const struct ref *dep,
 				exit(1);
 		}
 		if ((pkg->flags & QPKG_INSTALLED) || pkg->mark) {
-			assert(!conflicts(pkg, conf));
+			assert(!old_conflicts(pkg, conf));
 			resolve(next_dep, dep->next, top, conf);
 			continue;
 		}
-		if (conflicts(pkg, conf))
+		if (old_conflicts(pkg, conf))
+			continue;
+		if (new_conflicts(pkg->conflicts))
 			continue;
 		level++;
 		append_install(pkg);
@@ -268,7 +285,7 @@ struct pkg **prereq(struct pkg *pkg)
 		.next = installed_conflicts()
 	};
 
-	if (conflicts(pkg, &conf)) {
+	if (old_conflicts(pkg, &conf) || new_conflicts(pkg->conflicts)) {
 		fprintf(stderr, "%.*s conflicts with installed packages\n",
 		  ID2PF(pkg->id));
 		exit(1);
diff --git a/qpkg/test/conflict b/qpkg/test/conflict
index aa72f81..314fbc7 100755
--- a/qpkg/test/conflict
+++ b/qpkg/test/conflict
@@ -155,3 +155,70 @@ EOF
 expect <<EOF
 bar_0
 EOF
+
+###############################################################################
+
+qpkg_fail "prerequisite conflicts with dependant" prereq A <<EOF
+Package: B
+Version: 0
+Architecture: test
+Conflicts: A
+Filename: B
+
+Package: A
+Version: 0
+Architecture: test
+Depends: B
+Filename: A
+EOF
+expect <<EOF
+can't resolve A
+EOF
+
+###############################################################################
+
+qpkg_fail "prerequisite conflicts with considered package (1)" prereq A <<EOF
+Package: B
+Version: 0
+Architecture: test
+Conflicts: C
+Filename: B
+
+Package: C
+Version: 0
+Architecture: test
+Filename: C
+
+Package: A
+Version: 0
+Architecture: test
+Depends: B, C
+Filename: A
+EOF
+expect <<EOF
+can't resolve A
+EOF
+
+###############################################################################
+
+qpkg_fail "prerequisite conflicts with considered package (1)" prereq A <<EOF
+Package: B
+Version: 0
+Architecture: test
+Filename: B
+
+Package: C
+Version: 0
+Architecture: test
+Conflicts: B
+Filename: C
+
+Package: A
+Version: 0
+Architecture: test
+Depends: B, C
+Filename: A
+EOF
+expect <<EOF
+can't resolve A
+EOF
diff --git a/qpkg/test/instconf b/qpkg/test/instconf
index 853528f..eaa7993 100755
--- a/qpkg/test/instconf
+++ b/qpkg/test/instconf
@@ -48,3 +48,44 @@ EOF
 expect <<EOF
 A conflicts with installed packages
 EOF
+
+###############################################################################
+
+qpkg_fail "prerequisite conflicts with installed package" prereq A <<EOF
+Package: B
+Version: 0
+Architecture: test
+Conflicts: C
+Filename: B
+
+Package: A
+Version: 0
+Architecture: test
+Depends: B
+Filename: A
+
+Package: C
+Version: 0
+Architecture: test
+Status: installed
+EOF
+expect <<EOF
+can't resolve A
+EOF
+
+###############################################################################
+
+qpkg_fail "initial package conflicts with installed package" prereq A <<EOF
+Package: A
+Version: 0
+Architecture: test
+Conflicts: C
+Filename: A
+
+Package: C
+Version: 0
+Architecture: test
+Status: installed
+EOF
+expect <<EOF
+A conflicts with installed packages