diff --git a/qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/instances/QInstanceEnricher.java b/qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/instances/QInstanceEnricher.java
index 1d88cb7e..a0d926c0 100644
--- a/qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/instances/QInstanceEnricher.java
+++ b/qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/instances/QInstanceEnricher.java
@@ -23,6 +23,9 @@ package com.kingsrook.qqq.backend.core.instances;
 
 
 import java.io.Serializable;
+import java.lang.reflect.Method;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
@@ -33,8 +36,10 @@ import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
+import com.kingsrook.qqq.backend.core.actions.customizers.QCodeLoader;
 import com.kingsrook.qqq.backend.core.actions.metadata.JoinGraph;
 import com.kingsrook.qqq.backend.core.actions.permissions.BulkTableActionProcessPermissionChecker;
+import com.kingsrook.qqq.backend.core.actions.values.QCustomPossibleValueProvider;
 import com.kingsrook.qqq.backend.core.exceptions.QException;
 import com.kingsrook.qqq.backend.core.logging.QLogger;
 import com.kingsrook.qqq.backend.core.model.metadata.QBackendMetaData;
@@ -89,6 +94,7 @@ import com.kingsrook.qqq.backend.core.scheduler.QScheduleManager;
 import com.kingsrook.qqq.backend.core.utils.CollectionUtils;
 import com.kingsrook.qqq.backend.core.utils.ListingHash;
 import com.kingsrook.qqq.backend.core.utils.StringUtils;
+import static com.kingsrook.qqq.backend.core.logging.LogUtils.logPair;
 
 
 /*******************************************************************************
@@ -1347,6 +1353,60 @@ public class QInstanceEnricher
             }
          }
 
+         if(possibleValueSource.getIdType() == null)
+         {
+            QTableMetaData table = qInstance.getTable(possibleValueSource.getTableName());
+            if(table != null)
+            {
+               String         primaryKeyField         = table.getPrimaryKeyField();
+               QFieldMetaData primaryKeyFieldMetaData = table.getFields().get(primaryKeyField);
+               if(primaryKeyFieldMetaData != null)
+               {
+                  possibleValueSource.setIdType(primaryKeyFieldMetaData.getType());
+               }
+            }
+         }
+      }
+      else if(QPossibleValueSourceType.ENUM.equals(possibleValueSource.getType()))
+      {
+         if(possibleValueSource.getIdType() == null)
+         {
+            if(CollectionUtils.nullSafeHasContents(possibleValueSource.getEnumValues()))
+            {
+               Object id = possibleValueSource.getEnumValues().get(0).getId();
+               try
+               {
+                  possibleValueSource.setIdType(QFieldType.fromClass(id.getClass()));
+               }
+               catch(Exception e)
+               {
+                  LOG.warn("Error enriching possible value source with idType based on first enum value", e, logPair("possibleValueSource", possibleValueSource.getName()), logPair("id", id));
+               }
+            }
+         }
+      }
+      else if(QPossibleValueSourceType.CUSTOM.equals(possibleValueSource.getType()))
+      {
+         if(possibleValueSource.getIdType() == null)
+         {
+            try
+            {
+               QCustomPossibleValueProvider<?> customPossibleValueProvider = QCodeLoader.getCustomPossibleValueProvider(possibleValueSource);
+
+               Method getPossibleValueMethod = customPossibleValueProvider.getClass().getDeclaredMethod("getPossibleValue", Serializable.class);
+               Type   returnType             = getPossibleValueMethod.getGenericReturnType();
+               Type   idType                 = ((ParameterizedType) returnType).getActualTypeArguments()[0];
+
+               if(idType instanceof Class<?> c)
+               {
+                  possibleValueSource.setIdType(QFieldType.fromClass(c));
+               }
+            }
+            catch(Exception e)
+            {
+               LOG.warn("Error enriching possible value source with idType based on first custom value", e, logPair("possibleValueSource", possibleValueSource.getName()));
+            }
+         }
       }
    }
 
diff --git a/qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/instances/QInstanceValidator.java b/qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/instances/QInstanceValidator.java
index 58618c3e..a1edd5a9 100644
--- a/qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/instances/QInstanceValidator.java
+++ b/qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/instances/QInstanceValidator.java
@@ -2075,6 +2075,8 @@ public class QInstanceValidator
             default -> errors.add("Unexpected possibleValueSource type: " + possibleValueSource.getType());
          }
 
+         assertCondition(possibleValueSource.getIdType() != null, "possibleValueSource " + name + " is missing its idType.");
+
          runPlugins(QPossibleValueSource.class, possibleValueSource, qInstance);
       }
    }
diff --git a/qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/model/metadata/possiblevalues/QPossibleValueSource.java b/qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/model/metadata/possiblevalues/QPossibleValueSource.java
index e8fc860b..00b121b4 100644
--- a/qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/model/metadata/possiblevalues/QPossibleValueSource.java
+++ b/qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/model/metadata/possiblevalues/QPossibleValueSource.java
@@ -28,6 +28,7 @@ import com.kingsrook.qqq.backend.core.model.actions.tables.query.QFilterOrderBy;
 import com.kingsrook.qqq.backend.core.model.metadata.QInstance;
 import com.kingsrook.qqq.backend.core.model.metadata.TopLevelMetaDataInterface;
 import com.kingsrook.qqq.backend.core.model.metadata.code.QCodeReference;
+import com.kingsrook.qqq.backend.core.model.metadata.fields.QFieldType;
 
 
 /*******************************************************************************
@@ -42,6 +43,8 @@ public class QPossibleValueSource implements TopLevelMetaDataInterface
    private String                   label;
    private QPossibleValueSourceType type;
 
+   private QFieldType idType;
+
    private String       valueFormat           = PVSValueFormatAndFields.LABEL_ONLY.getFormat();
    private List<String> valueFields           = PVSValueFormatAndFields.LABEL_ONLY.getFields();
    private String       valueFormatIfNotFound = null;
@@ -662,4 +665,35 @@ public class QPossibleValueSource implements TopLevelMetaDataInterface
       return (this);
    }
 
+
+   /*******************************************************************************
+    ** Getter for idType
+    *******************************************************************************/
+   public QFieldType getIdType()
+   {
+      return (this.idType);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for idType
+    *******************************************************************************/
+   public void setIdType(QFieldType idType)
+   {
+      this.idType = idType;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for idType
+    *******************************************************************************/
+   public QPossibleValueSource withIdType(QFieldType idType)
+   {
+      this.idType = idType;
+      return (this);
+   }
+
+
 }