diff --git a/recipe/meta.yaml b/recipe/meta.yaml
index 6d2df633..de3eb845 100644
--- a/recipe/meta.yaml
+++ b/recipe/meta.yaml
@@ -14,7 +14,7 @@ source:
     - osx_rpath.patch  # [osx]
 
 build:
-  number: 2
+  number: 3
   skip: true  # [not py27]
 
 requirements:
@@ -24,19 +24,19 @@ requirements:
     - numpy x.x
     - eigen 3.*
     - jasper   # [unix]
-    - zlib 1.2*
+    - zlib 1.2.*
     - jpeg 9*
     - libtiff 4.0.*
-    - libpng 1.6*
+    - libpng >=1.6.23,<1.7
 
   run:
     - python
     - numpy x.x
     - jasper   # [unix]
-    - zlib 1.2*
+    - zlib 1.2.*
     - jpeg 9*
     - libtiff 4.0.*
-    - libpng 1.6*
+    - libpng >=1.6.23,<1.7
 
 test:
   imports: