diff --git a/components/formats-gpl/pom.xml b/components/formats-gpl/pom.xml
index 404a7b107c1..52bdffc7a97 100644
--- a/components/formats-gpl/pom.xml
+++ b/components/formats-gpl/pom.xml
@@ -65,8 +65,8 @@
     </dependency>
     <dependency>
       <groupId>edu.ucar</groupId>
-      <artifactId>cdm</artifactId>
-      <version>4.6.13</version>
+      <artifactId>cdm-core</artifactId>
+      <version>5.3.3</version>
       <exclusions>
         <exclusion>
           <groupId>com.amazonaws</groupId>
@@ -275,7 +275,7 @@
                 <additionalClasspathElement>${basedir}/../../ant/</additionalClasspathElement>
               </additionalClasspathElements>
               <classpathDependencyExcludes>
-                <classpathDependencyExclude>edu.ucar:cdm</classpathDependencyExclude>
+                <classpathDependencyExclude>edu.ucar:cdm-core</classpathDependencyExclude>
               </classpathDependencyExcludes>
               <systemPropertyVariables>
                 <bioformats_can_do_upgrade_check>false</bioformats_can_do_upgrade_check>
diff --git a/components/formats-gpl/src/loci/formats/in/MINCReader.java b/components/formats-gpl/src/loci/formats/in/MINCReader.java
index ef37e886aef..10b04bc37e4 100644
--- a/components/formats-gpl/src/loci/formats/in/MINCReader.java
+++ b/components/formats-gpl/src/loci/formats/in/MINCReader.java
@@ -157,9 +157,11 @@ protected void initFile(String id) throws FormatException, IOException {
       boolean signed = false;
       if (isMINC2) {
         Hashtable<String, Object> attrs = netcdf.getVariableAttributes("/minc-2.0/image/0/image");
-        String unsigned = attrs.get("_Unsigned").toString();
-        if (!unsigned.startsWith("true")) {
-          signed = true;
+        if (attrs.get("_Unsigned") != null) {
+          String unsigned = attrs.get("_Unsigned").toString();
+          if (!unsigned.startsWith("true")) {
+            signed = true;
+          }
         }
       }
       else {
diff --git a/components/formats-gpl/test/loci/formats/utests/NetCDFServiceTest.java b/components/formats-gpl/test/loci/formats/utests/NetCDFServiceTest.java
index f484e2d081d..fe451bf8fd1 100644
--- a/components/formats-gpl/test/loci/formats/utests/NetCDFServiceTest.java
+++ b/components/formats-gpl/test/loci/formats/utests/NetCDFServiceTest.java
@@ -124,7 +124,6 @@ public class NetCDFServiceTest {
     {"PAL_COLORMODEL", "RGB"},
     {"PAL_TYPE", "STANDARD8"},
     {"PAL_VERSION", "1.2"},
-    {"_Unsigned", "true"},
     },
     {
     {"CLASS", "IMAGE"},
@@ -136,7 +135,6 @@ public class NetCDFServiceTest {
     {"IMAGE_SUBCLASS", "IMAGE_INDEXED"},
     {"IMAGE_VERSION", "1.2"},
     {"PALETTE", "1680"},
-    {"_Unsigned", "true"},
     }
   };