diff --git a/solr/CHANGES.txt b/solr/CHANGES.txt
index 9900f4a37c6..ef919a8ee8b 100644
--- a/solr/CHANGES.txt
+++ b/solr/CHANGES.txt
@@ -134,6 +134,10 @@ Bug Fixes
 * SOLR-3623: Fixed inconsistent treatment of third-party dependencies for 
   solr contribs analysis-extras & uima (hossman) 
 
+* SOLR-3652: Fixed range faceting to error instead of looping infinitely 
+  when 'gap' is zero -- or effectively zero due to floating point arithmetic 
+  underflow. (hossman)
+
 Other Changes
 ----------------------
 
diff --git a/solr/core/src/java/org/apache/solr/request/SimpleFacets.java b/solr/core/src/java/org/apache/solr/request/SimpleFacets.java
index a1e9823a48e..f25e7aa4182 100644
--- a/solr/core/src/java/org/apache/solr/request/SimpleFacets.java
+++ b/solr/core/src/java/org/apache/solr/request/SimpleFacets.java
@@ -924,6 +924,11 @@ public class SimpleFacets {
               (SolrException.ErrorCode.BAD_REQUEST,
                   "date facet infinite loop (is gap negative?)");
         }
+        if (high.equals(low)) {
+          throw new SolrException
+            (SolrException.ErrorCode.BAD_REQUEST,
+             "date facet infinite loop: gap is effectively zero");
+        }
         final boolean includeLower =
             (include.contains(FacetRangeInclude.LOWER) ||
                 (include.contains(FacetRangeInclude.EDGE) && low.equals(start)));
@@ -1113,6 +1118,11 @@ public class SimpleFacets {
           (SolrException.ErrorCode.BAD_REQUEST,
            "range facet infinite loop (is gap negative? did the math overflow?)");
       }
+      if (high.compareTo(low) == 0) {
+        throw new SolrException
+          (SolrException.ErrorCode.BAD_REQUEST,
+           "range facet infinite loop: gap is either zero, or too small relative start/end and caused underflow: " + low + " + " + gap + " = " + high );
+      }
       
       final boolean includeLower = 
         (include.contains(FacetRangeInclude.LOWER) ||
diff --git a/solr/core/src/test/org/apache/solr/request/SimpleFacetsTest.java b/solr/core/src/test/org/apache/solr/request/SimpleFacetsTest.java
index 5ea20ee9804..e251ed6398f 100644
--- a/solr/core/src/test/org/apache/solr/request/SimpleFacetsTest.java
+++ b/solr/core/src/test/org/apache/solr/request/SimpleFacetsTest.java
@@ -2004,4 +2004,61 @@ public class SimpleFacetsTest extends SolrTestCaseJ4 {
             ,"*[count(//lst[@name='facet_fields']/lst/int)=0]"
     );
   }
+
+  /** 
+   * kind of an absurd tests because if there is an inifnite loop, it 
+   * would ver finish -- but at least it ensures that <i>if</i> one of 
+   * these requests return, they return an error 
+   */
+  public void testRangeFacetInfiniteLoopDetection() {
+
+    for (String field : new String[] {"foo_f", "foo_sf", 
+                                      "foo_d", "foo_sd",
+                                      "foo_i", "foo_si"}) {
+      assertQEx("no zero gap error: " + field,
+                req("q", "*:*",
+                    "facet", "true",
+                    "facet.range", field,
+                    "facet.range.start", "23",
+                    "facet.range.gap", "0",
+                    "facet.range.end", "100"),
+                400);
+    }
+    for (String field : new String[] {"foo_pdt", "foo_dt"}) {
+      for (String type : new String[] {"date", "range"}) {
+      assertQEx("no zero gap error for facet." + type + ": " + field,
+                req("q", "*:*",
+                    "facet", "true",
+                    "facet." + type, field,
+                    "facet."+type+".start", "NOW",
+                    "facet."+type+".gap", "+0DAYS",
+                    "facet."+type+".end", "NOW+10DAY"),
+                400);
+      }
+    }
+    
+    for (String field : new String[] {"foo_f", "foo_sf"}) {
+      assertQEx("no float underflow error: " + field,
+                req("q", "*:*",
+                    "facet", "true",
+                    "facet.range", field,
+                    "facet.range.start", "100000000000",
+                    "facet.range.end", "100000086200",
+                    "facet.range.gap", "2160"),
+                400);
+    }
+
+    for (String field : new String[] {"foo_d", "foo_sd"}) {
+      assertQEx("no double underflow error: " + field,
+                req("q", "*:*",
+                    "facet", "true",
+                    "facet.range", field,
+                    "facet.range.start", "9900000000000",
+                    "facet.range.end", "9900000086200",
+                    "facet.range.gap", "0.0003"),
+                400);
+    }
+    
+  }
+
 }