diff --git a/langtools/src/share/classes/com/sun/tools/javap/JavapTask.java b/langtools/src/share/classes/com/sun/tools/javap/JavapTask.java
index 6033433d40e..4099f95d5cb 100644
--- a/langtools/src/share/classes/com/sun/tools/javap/JavapTask.java
+++ b/langtools/src/share/classes/com/sun/tools/javap/JavapTask.java
@@ -273,7 +273,9 @@ public class JavapTask implements DisassemblerTool.DisassemblerTask, Messages {
             void process(JavapTask task, String opt, String arg) throws BadArgs {
                 int sep = opt.indexOf(":");
                 try {
-                    task.options.indentWidth = Integer.valueOf(opt.substring(sep + 1));
+                    int i = Integer.valueOf(opt.substring(sep + 1));
+                    if (i > 0) // silently ignore invalid values
+                        task.options.indentWidth = i;
                 } catch (NumberFormatException e) {
                 }
             }
@@ -289,7 +291,9 @@ public class JavapTask implements DisassemblerTool.DisassemblerTask, Messages {
             void process(JavapTask task, String opt, String arg) throws BadArgs {
                 int sep = opt.indexOf(":");
                 try {
-                    task.options.tabColumn = Integer.valueOf(opt.substring(sep + 1));
+                    int i = Integer.valueOf(opt.substring(sep + 1));
+                    if (i > 0) // silently ignore invalid values
+                        task.options.tabColumn = i;
                 } catch (NumberFormatException e) {
                 }
             }
diff --git a/langtools/src/share/classes/com/sun/tools/javap/Options.java b/langtools/src/share/classes/com/sun/tools/javap/Options.java
index fbfc30b2190..3723fc3afe0 100644
--- a/langtools/src/share/classes/com/sun/tools/javap/Options.java
+++ b/langtools/src/share/classes/com/sun/tools/javap/Options.java
@@ -86,6 +86,6 @@ public class Options {
     public boolean showConstants;
     public boolean sysInfo;
     public boolean showInnerClasses;
-    public int indentWidth = 2;   // #spaces per indentWidth level
-    public int tabColumn = 40;    // column number for comments
+    public int indentWidth = 2;   // #spaces per indentWidth level; must be > 0
+    public int tabColumn = 40;    // column number for comments; must be > 0
 }