diff --git a/sof-js/src/index.js b/sof-js/src/index.js
index 8c5772e..0b8106e 100644
--- a/sof-js/src/index.js
+++ b/sof-js/src/index.js
@@ -113,7 +113,9 @@ function select(select_expr, node, def) {
   assert(select_expr.select, 'select')
   if(select_expr.where) {
     let include = select_expr.where.every((w)=>{
-      return fhirpath_evaluate(node, w.path, def.constant)[0]
+      const val = fhirpath_evaluate(node, w.path, def.constant)[0]
+      assert(typeof val === "boolean", "'where' expression path should return 'boolean'")
+      return val
     })
     if(!include) { return []}
   }
diff --git a/sof-js/tests/1_basic.test.js b/sof-js/tests/1_basic.test.js
index e5e643d..2745369 100644
--- a/sof-js/tests/1_basic.test.js
+++ b/sof-js/tests/1_basic.test.js
@@ -153,7 +153,7 @@ describe("basics", () => {
       resource: 'Patient',
       status: 'active',
       select: [{column: [{name: 'id', path: 'id'}]}],
-      where: [{path: 'active = true'}]
+      where: [{path: 'active.exists() and active = true'}]
     },
     expect: [{id: 'pt1'}]
   })
@@ -164,13 +164,13 @@ describe("basics", () => {
       resource: 'Patient',
       status: 'active',
       select: [{column: [{name: 'id', path: 'id'}]}],
-      where: [{path: 'active = false'}]
+      where: [{path: 'active.exists() and active = false'}]
     },
     expect: [{id: 'pt2'}]
   })
 
-  add_test({
-    title: 'where as element',
+  add_throwing_test({
+    title: 'where returns non-boolean for some cases',
     view: {
       resource: 'Patient',
       status: 'active',
@@ -186,7 +186,7 @@ describe("basics", () => {
       resource: 'Patient',
       status: 'active',
       select: [{column: [{name: 'id', path: 'id'}]}],
-      where: [{path: "name.family = 'F2'"}]
+      where: [{path: "name.family.exists() and name.family = 'F2'"}]
     },
     expect: [{id: 'pt2'}]
   })
@@ -197,7 +197,7 @@ describe("basics", () => {
       resource: 'Patient',
       status: 'active',
       select: [{column: [{name: 'id', path: 'id'}]}],
-      where: [{path: "name.family = 'F1'"}]
+      where: [{path: "name.family.exists() and name.family = 'F1'"}]
     },
     expect: [{id: 'pt1'}]
   })
diff --git a/sof-js/tests/5_constants.test.js b/sof-js/tests/5_constants.test.js
index 9d1237c..9a4d847 100644
--- a/sof-js/tests/5_constants.test.js
+++ b/sof-js/tests/5_constants.test.js
@@ -94,7 +94,7 @@ describe("constant", () => {
           column: [{ name: "id", path: "id" }]
         }
       ],
-      where: [{ path: "name.where(use = %name_use)" }]
+      where: [{ path: "name.where(use = %name_use).exists()" }]
     },
     expect: [{ id: "pt1" }]
   });
@@ -168,7 +168,7 @@ describe("constant", () => {
           column: [{ name: "id", path: "id" }]
         }
       ],
-      where: [{ path: "deceased.ofType(boolean) = %is_deceased" }]
+      where: [{ path: "deceased.ofType(boolean).exists() and deceased.ofType(boolean) = %is_deceased" }]
     },
     expect: [{ id: "pt2" }]
   });
diff --git a/sof-js/tests/validation.test.js b/sof-js/tests/validation.test.js
index 41fe22e..5d7b299 100644
--- a/sof-js/tests/validation.test.js
+++ b/sof-js/tests/validation.test.js
@@ -1,10 +1,13 @@
 import { describe } from "bun:test";
-import { start_case, end_case, invalid_view, debug } from './test_helpers.js'
+import { start_case, end_case, invalid_view, debug, add_throwing_test } from './test_helpers.js'
 
 
 let resources = [
   {
     resourceType: 'Patient',
+    name: [
+      { family: 'F1.1' },
+    ],
     id: 'pt1'
   },
   {
diff --git a/tests/basic.json b/tests/basic.json
index caf877c..866093a 100644
--- a/tests/basic.json
+++ b/tests/basic.json
@@ -182,7 +182,7 @@
         ],
         "where": [
           {
-            "path": "active = true"
+            "path": "active.exists() and active = true"
           }
         ]
       },
@@ -209,7 +209,7 @@
         ],
         "where": [
           {
-            "path": "active = false"
+            "path": "active.exists() and active = false"
           }
         ]
       },
@@ -220,7 +220,7 @@
       ]
     },
     {
-      "title": "where as element",
+      "title": "where returns non-boolean for some cases",
       "view": {
         "resource": "Patient",
         "status": "active",
@@ -263,7 +263,7 @@
         ],
         "where": [
           {
-            "path": "name.family = 'F2'"
+            "path": "name.family.exists() and name.family = 'F2'"
           }
         ]
       },
@@ -290,7 +290,7 @@
         ],
         "where": [
           {
-            "path": "name.family = 'F1'"
+            "path": "name.family.exists() and name.family = 'F1'"
           }
         ]
       },
diff --git a/tests/constant.json b/tests/constant.json
index ef19fce..bc16729 100644
--- a/tests/constant.json
+++ b/tests/constant.json
@@ -122,7 +122,7 @@
         ],
         "where": [
           {
-            "path": "name.where(use = %name_use)"
+            "path": "name.where(use = %name_use).exists()"
           }
         ]
       },
@@ -244,7 +244,7 @@
         ],
         "where": [
           {
-            "path": "deceased.ofType(boolean) = %is_deceased"
+            "path": "deceased.ofType(boolean).exists() and deceased.ofType(boolean) = %is_deceased"
           }
         ]
       },
diff --git a/tests/validate.json b/tests/validate.json
index 141523c..f4030fa 100644
--- a/tests/validate.json
+++ b/tests/validate.json
@@ -4,6 +4,11 @@
   "resources": [
     {
       "resourceType": "Patient",
+      "name": [
+        {
+          "family": "F1.1"
+        }
+      ],
       "id": "pt1"
     },
     {
@@ -15,7 +20,7 @@
     {
       "title": "empty",
       "view": {},
-      "error": "structure"
+      "expectError": true
     },
     {
       "title": "wrong fhirpath",
@@ -28,10 +33,10 @@
           }
         ]
       },
-      "error": "fhirpath"
+      "expectError": true
     },
     {
-      "title": "wrong type",
+      "title": "wrong type in forEach",
       "view": {
         "resource": "Patient",
         "status": "active",
@@ -41,7 +46,30 @@
           }
         ]
       },
-      "error": "structure"
+      "expectError": true
+    },
+    {
+      "title": "where with path resolving to not boolean",
+      "view": {
+        "resource": "Patient",
+        "status": "active",
+        "select": [
+          {
+            "column": [
+              {
+                "name": "id",
+                "path": "id"
+              }
+            ]
+          }
+        ],
+        "where": [
+          {
+            "path": "name.family"
+          }
+        ]
+      },
+      "expectError": true
     }
   ]
 }