diff --git a/src/main/java/gov/nasa/pds/tools/validate/SpecialConstantChecker.java b/src/main/java/gov/nasa/pds/tools/validate/SpecialConstantChecker.java
index 069d1b69d..d0c30be71 100644
--- a/src/main/java/gov/nasa/pds/tools/validate/SpecialConstantChecker.java
+++ b/src/main/java/gov/nasa/pds/tools/validate/SpecialConstantChecker.java
@@ -28,19 +28,22 @@ public static boolean isInfOrNan (String value) {
    * @param constants
    * @return
    */
+  private static boolean equalsStripped(String value, String constant) {
+    return constant != null && value.equals(constant.strip());
+  }
   public static boolean isNonConformantSpecialConstant(String value, SpecialConstants constants) {
     boolean matched = false;
     if (constants != null) {
-      matched |= value.equals(constants.getErrorConstant());
-      matched |= value.equals(constants.getInvalidConstant());
-      matched |= value.equals(constants.getMissingConstant());
-      //matched |= value.equals(constants.getHighInstrumentSaturation());
-      //matched |= value.equals(constants.getHighRepresentationSaturation());
-      //matched |= value.equals(constants.getLowInstrumentSaturation());
-      //matched |= value.equals(constants.getLowRepresentationSaturation());
-      matched |= value.equals(constants.getNotApplicableConstant());
-      matched |= value.equals(constants.getSaturatedConstant());
-      matched |= value.equals(constants.getUnknownConstant());
+      matched |= equalsStripped(value, constants.getErrorConstant());
+      matched |= equalsStripped(value, constants.getInvalidConstant());
+      matched |= equalsStripped(value, constants.getMissingConstant());
+      //matched |= equalsStripped(value, constants.getHighInstrumentSaturation());
+      //matched |= equalsStripped(value, constants.getHighRepresentationSaturation());
+      //matched |= equalsStripped(value, constants.getLowInstrumentSaturation());
+      //matched |= equalsStripped(value, constants.getLowRepresentationSaturation());
+      matched |= equalsStripped(value, constants.getNotApplicableConstant());
+      matched |= equalsStripped(value, constants.getSaturatedConstant());
+      matched |= equalsStripped(value, constants.getUnknownConstant());
     }
     return matched;
   }
@@ -164,6 +167,7 @@ public static boolean isConformantSpecialConstant(Number value, SpecialConstants
   }
   public static boolean sameContent (Number number, String constant_repr, int radix) {
     if (constant_repr == null) return false;
+    constant_repr = constant_repr.strip();
     if (number.toString().equals(constant_repr)) {
       return true;
     }
diff --git a/src/test/resources/features/4.2.x.feature b/src/test/resources/features/4.2.x.feature
index 049d05b68..cdf3dfa6e 100644
--- a/src/test/resources/features/4.2.x.feature
+++ b/src/test/resources/features/4.2.x.feature
@@ -20,4 +20,7 @@ Feature: 4.2.x
 # github1660: missing_constant must suppress min/max range errors in ASCII table fields
 | 1660 | 1 | "github1660" | "--skip-context-validation -t {datasrc}/pccds.xml" | "summary:productValidation:passed=1,summary:totalErrors=0,summary:totalWarnings=2,summary:messageTypes:warning.label.bad_schematypens=1,summary:messageTypes:warning.label.missing_schematron_spec=1" |
 
+# github1656: missing_constant with leading/trailing whitespace must suppress min/max range errors
+| 1656 | 1 | "github1656" | "--skip-context-validation -t {datasrc}/test_missing_constant_whitespace.xml" | "summary:productValidation:passed=1,summary:totalErrors=0,summary:totalWarnings=2,summary:messageTypes:warning.label.bad_schematypens=1,summary:messageTypes:warning.label.missing_schematron_spec=1" |
+
 #end
diff --git a/src/test/resources/github1656/test_missing_constant_whitespace.csv b/src/test/resources/github1656/test_missing_constant_whitespace.csv
new file mode 100644
index 000000000..73d237f21
--- /dev/null
+++ b/src/test/resources/github1656/test_missing_constant_whitespace.csv
@@ -0,0 +1,3 @@
+1.500,-1.000
+2.300,-1.000
+0.750,5.000
diff --git a/src/test/resources/github1656/test_missing_constant_whitespace.xml b/src/test/resources/github1656/test_missing_constant_whitespace.xml
new file mode 100644
index 000000000..b1a5918ad
--- /dev/null
+++ b/src/test/resources/github1656/test_missing_constant_whitespace.xml
@@ -0,0 +1,86 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<?xml-model href="http://pds.nasa.gov/pds4/pds/v1/PDS4_PDS_1B00.sch" schemtatypens="http://purl.oclc.org/dsdl/schematron"?>
+
+<Product_Observational xmlns="http://pds.nasa.gov/pds4/pds/v1"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://pds.nasa.gov/pds4/pds/v1 http://pds.nasa.gov/pds4/pds/v1/PDS4_PDS_1B00.xsd">
+
+    <Identification_Area>
+        <logical_identifier>urn:nasa:pds:test:data:missing_constant_whitespace</logical_identifier>
+        <version_id>1.0</version_id>
+        <title>Test: missing_constant with leading whitespace should suppress min/max warnings</title>
+        <information_model_version>1.11.0.0</information_model_version>
+        <product_class>Product_Observational</product_class>
+    </Identification_Area>
+
+    <Observation_Area>
+        <Time_Coordinates>
+            <start_date_time>2020-01-01Z</start_date_time>
+            <stop_date_time>2020-12-31Z</stop_date_time>
+        </Time_Coordinates>
+        <Primary_Result_Summary>
+            <purpose>Science</purpose>
+            <processing_level>Derived</processing_level>
+        </Primary_Result_Summary>
+        <Investigation_Area>
+            <name>None</name>
+            <type>Other Investigation</type>
+            <Internal_Reference>
+                <lid_reference>urn:nasa:pds:context:investigation:individual.none</lid_reference>
+                <reference_type>data_to_investigation</reference_type>
+            </Internal_Reference>
+        </Investigation_Area>
+        <Observing_System>
+            <Observing_System_Component>
+                <name>Test Instrument</name>
+                <type>Instrument</type>
+            </Observing_System_Component>
+        </Observing_System>
+        <Target_Identification>
+            <name>Test Target</name>
+            <type>Comet</type>
+        </Target_Identification>
+    </Observation_Area>
+
+    <File_Area_Observational>
+        <File>
+            <file_name>test_missing_constant_whitespace.csv</file_name>
+            <records>3</records>
+        </File>
+        <Table_Delimited>
+            <name>Test Table</name>
+            <local_identifier>TABLE</local_identifier>
+            <offset unit="byte">0</offset>
+            <parsing_standard_id>PDS DSV 1</parsing_standard_id>
+            <records>3</records>
+            <record_delimiter>Carriage-Return Line-Feed</record_delimiter>
+            <field_delimiter>Comma</field_delimiter>
+            <Record_Delimited>
+                <fields>2</fields>
+                <groups>0</groups>
+                <Field_Delimited>
+                    <name>measurement</name>
+                    <field_number>1</field_number>
+                    <data_type>ASCII_Real</data_type>
+                    <Field_Statistics>
+                        <maximum>10000.0</maximum>
+                        <minimum>0.001</minimum>
+                    </Field_Statistics>
+                </Field_Delimited>
+                <Field_Delimited>
+                    <name>quality_flag</name>
+                    <field_number>2</field_number>
+                    <data_type>ASCII_Real</data_type>
+                    <Special_Constants>
+                        <missing_constant>   -1.000</missing_constant>
+                    </Special_Constants>
+                    <Field_Statistics>
+                        <maximum>10000.000</maximum>
+                        <minimum>0.001</minimum>
+                    </Field_Statistics>
+                </Field_Delimited>
+            </Record_Delimited>
+        </Table_Delimited>
+    </File_Area_Observational>
+
+</Product_Observational>