diff --git a/core/src/main/java/hudson/model/Hudson.java b/core/src/main/java/hudson/model/Hudson.java
index 2fcc327bd300f5067e6742a67d97fb2f88087093..e126a00d545f8a88c2ccfce70b53ca4689e73870 100644
--- a/core/src/main/java/hudson/model/Hudson.java
+++ b/core/src/main/java/hudson/model/Hudson.java
@@ -1423,6 +1423,10 @@ public final class Hudson extends Node implements ItemGroup<TopLevelItem>, Stapl
             return false;
         }
 
+        public FormValidation doCheckNumExecutors(@QueryParameter String value) {
+            return FormValidation.validateNonNegativeInteger(value);
+        }
+
         // to route /descriptor/FQCN/xxx to getDescriptor(FQCN).xxx
         public Object getDynamic(String token) {
             return Hudson.getInstance().getDescriptor(token);
diff --git a/core/src/main/java/hudson/model/Slave.java b/core/src/main/java/hudson/model/Slave.java
index f563dde984d395070b285dd9fc56d024d2ec6b20..b50fa00f950255082ad875f1149009efd10b99ea 100644
--- a/core/src/main/java/hudson/model/Slave.java
+++ b/core/src/main/java/hudson/model/Slave.java
@@ -427,7 +427,7 @@ public abstract class Slave extends Node implements Serializable {
 
     public static abstract class SlaveDescriptor extends NodeDescriptor {
         public FormValidation doCheckNumExecutors(@QueryParameter String value) {
-            return FormValidation.validateNonNegativeInteger(value);
+            return FormValidation.validatePositiveInteger(value);
         }
 
         /**
diff --git a/core/src/main/java/hudson/util/FormValidation.java b/core/src/main/java/hudson/util/FormValidation.java
index c0bd3c4dc53c7eac4f826813d2aad4c9e81ebeae..1fdbd833c7d050fc62f8ae04eef0b3760122e8cc 100644
--- a/core/src/main/java/hudson/util/FormValidation.java
+++ b/core/src/main/java/hudson/util/FormValidation.java
@@ -299,6 +299,19 @@ public abstract class FormValidation extends IOException implements HttpResponse
     public static FormValidation validateNonNegativeInteger(String value) {
         try {
             if(Integer.parseInt(value)<0)
+                return error(hudson.model.Messages.Hudson_NotANonNegativeNumber());
+            return ok();
+        } catch (NumberFormatException e) {
+            return error(hudson.model.Messages.Hudson_NotANumber());
+        }
+    }
+
+    /**
+     * Makes sure that the given string is a positive integer.
+     */
+    public static FormValidation validatePositiveInteger(String value) {
+        try {
+            if(Integer.parseInt(value)<=0)
                 return error(hudson.model.Messages.Hudson_NotAPositiveNumber());
             return ok();
         } catch (NumberFormatException e) {
diff --git a/core/src/main/resources/hudson/model/Messages.properties b/core/src/main/resources/hudson/model/Messages.properties
index 42f7d61d86425f933143410cc36957d4019cac19..16c531f0c9c85ccfabd8be3fae8f8d62fb95ee1d 100644
--- a/core/src/main/resources/hudson/model/Messages.properties
+++ b/core/src/main/resources/hudson/model/Messages.properties
@@ -88,6 +88,7 @@ Hudson.ViewAlreadyExists=A view already exists with the name "{0}"
 Hudson.ViewName=All
 Hudson.NotANumber=Not a number
 Hudson.NotAPositiveNumber=Not a positive number
+Hudson.NotANonNegativeNumber=Number may not be negative
 Hudson.NotANegativeNumber=Not a negative number
 Hudson.NotUsesUTF8ToDecodeURL=\
   Your container doesn''t use UTF-8 to decode URLs. If you use non-ASCII characters as a job name etc, \
diff --git a/core/src/main/resources/hudson/model/Node/help-numExecutors.html b/core/src/main/resources/hudson/model/Node/help-numExecutors.html
index 4c8fe55c47a3d91fb856999be28cfe64fcf7f46d..7e30307f29c1561084f778e8c6d044c88434f6a1 100644
--- a/core/src/main/resources/hudson/model/Node/help-numExecutors.html
+++ b/core/src/main/resources/hudson/model/Node/help-numExecutors.html
@@ -10,5 +10,6 @@
 
   <p>
   When using Hudson in the master/slave mode, setting this value to 0 would prevent the master
-  to do any build on its own.
-</div>
\ No newline at end of file
+  from doing any building on its own.  Slaves may not have zero executors, but may be
+  temporarily disabled using the button on the slave's status page.
+</div>