diff --git a/easybuild/easyconfigs/n/NSS/NSS-3.39-GCCcore-6.4.0.eb b/easybuild/easyconfigs/n/NSS/NSS-3.39-GCCcore-6.4.0.eb
index f386b75de3bf..889e4a9531d5 100644
--- a/easybuild/easyconfigs/n/NSS/NSS-3.39-GCCcore-6.4.0.eb
+++ b/easybuild/easyconfigs/n/NSS/NSS-3.39-GCCcore-6.4.0.eb
@@ -18,7 +18,10 @@ checksums = [
 ]
 
 builddependencies = [('binutils', '2.28')]
-dependencies = [('NSPR', '4.20')]
+dependencies = [
+    ('NSPR', '4.20'),
+    ('zlib', '1.2.11'),
+]
 
 # building in parallel fails
 parallel = 1
diff --git a/easybuild/easyconfigs/n/NSS/NSS-3.39-GCCcore-7.3.0.eb b/easybuild/easyconfigs/n/NSS/NSS-3.39-GCCcore-7.3.0.eb
index f903aa7aaa05..50e0978d6908 100644
--- a/easybuild/easyconfigs/n/NSS/NSS-3.39-GCCcore-7.3.0.eb
+++ b/easybuild/easyconfigs/n/NSS/NSS-3.39-GCCcore-7.3.0.eb
@@ -18,7 +18,10 @@ checksums = [
 ]
 
 builddependencies = [('binutils', '2.30')]
-dependencies = [('NSPR', '4.20')]
+dependencies = [
+    ('NSPR', '4.20'),
+    ('zlib', '1.2.11'),
+]
 
 # building in parallel fails
 parallel = 1