diff --git a/geom/geos/geos_test.go b/geom/geos/geos_test.go
index 3f9ab99..112e117 100644
--- a/geom/geos/geos_test.go
+++ b/geom/geos/geos_test.go
@@ -1,6 +1,10 @@
 package geos
 
-import "testing"
+import (
+	"fmt"
+
+	"testing"
+)
 
 func TestFoo(t *testing.T) {
 	_ = NewGeos()
@@ -23,3 +27,63 @@ func BenchmarkWKB(b *testing.B) {
 		g.Destroy(geom)
 	}
 }
+
+func TestIndexQuery(t *testing.T) {
+	g := NewGeos()
+	defer g.Finish()
+
+	idx := g.CreateIndex()
+
+	for i := 0; i < 10; i++ {
+		p := g.FromWkt(fmt.Sprintf("POLYGON((%d 0, 10 0, 10 10, %d 10, %d 0))", i, i, i))
+		if p == nil {
+			t.Fatal()
+		}
+		g.IndexAdd(idx, p)
+	}
+
+	if geoms := g.IndexQuery(idx, g.Point(0, 10.000001)); len(geoms) != 0 {
+		t.Fatal(geoms)
+	}
+
+	if geoms := g.IndexQuery(idx, g.Point(9.5, 5)); len(geoms) != 10 {
+		t.Fatal(geoms)
+	}
+
+	if geoms := g.IndexQuery(idx, g.Point(0.5, 5)); len(geoms) != 1 {
+		t.Fatal(geoms)
+	}
+	if geoms := g.IndexQuery(idx, g.Point(4.5, 5)); len(geoms) != 5 {
+		t.Fatal(geoms)
+	}
+
+}
+
+func BenchmarkIndexQuery(b *testing.B) {
+	g := NewGeos()
+	defer g.Finish()
+
+	idx := g.CreateIndex()
+	for i := 0; i < 10; i++ {
+		p := g.FromWkt(fmt.Sprintf("POLYGON((%d 0, 10 0, 10 10, %d 10, %d 0))", i, i, i))
+		if p == nil {
+			b.Fatal()
+		}
+		g.IndexAdd(idx, p)
+	}
+
+	for i := 0; i < b.N; i++ {
+		if geoms := g.IndexQuery(idx, g.Point(8.5, 5)); len(geoms) != 9 {
+			b.Fatal(geoms)
+		}
+	}
+
+	// if geoms := g.IndexQuery(idx, g.Point(0, 0)); len(geoms) != 10 {
+	// 	b.Fatal(geoms)
+	// }
+
+	// if geoms := g.IndexQuery(idx, g.Point(5, 5)); len(geoms) != 10 {
+	// 	b.Fatal(geoms)
+	// }
+
+}
diff --git a/geom/geos/geos_wrap.go b/geom/geos/geos_wrap.go
index 8e61cd4..b61d106 100644
--- a/geom/geos/geos_wrap.go
+++ b/geom/geos/geos_wrap.go
@@ -3,12 +3,13 @@ package geos
 /*
 #cgo LDFLAGS: -lgeos_c
 #include "geos_c.h"
+#include <stdint.h>
 #include <stdlib.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <string.h>
 
 extern void goLogString(char *msg);
-extern void goSendQueryResult(size_t, void *);
 
 void debug_wrap(const char *fmt, ...) {
 	va_list a_list;
@@ -31,9 +32,33 @@ void initGEOS_debug() {
     return initGEOS(devnull, debug_wrap);
 }
 
-// wrap goIndexSendQueryResult
-void IndexQuerySendCallback(void *item, void *userdata) {
-    goIndexSendQueryResult((size_t)item, userdata);
+typedef struct {
+    uint32_t num;
+    uint32_t *arr;
+    uint32_t arrCap;
+} queryResult;
+
+void queryResultAppend(queryResult *r, int idx) {
+    r->num += 1;
+    if (r->num >= r->arrCap) {
+        uint32_t newCap = r->arrCap > 0 ? r->arrCap * 2 : 8;
+        uint32_t *newArr = malloc(sizeof(uint32_t) * newCap);
+        if (r->arrCap == 0) {
+            r->arr = newArr;
+        } else {
+            memcpy(newArr, r->arr, r->num-1);
+            free(r->arr);
+            r->arr = newArr;
+        }
+        r->arrCap = newCap;
+    }
+    r->arr[r->num] = idx;
+}
+
+void IndexQueryCallback(void *item, void *userdata) {
+    int idx = (size_t)item;
+    queryResult *result = (queryResult *)userdata;
+    queryResultAppend(result, idx);
 }
 
 void IndexAdd(
@@ -47,14 +72,18 @@ void IndexAdd(
     GEOSSTRtree_insert_r(handle, tree, g, (void *)id);
 }
 
+
 // query with our custom callback
-void IndexQuery(
+uint32_t *IndexQuery(
     GEOSContextHandle_t handle,
     GEOSSTRtree *tree,
     const GEOSGeometry *g,
-    void *userdata)
+    uint32_t *num)
 {
-    GEOSSTRtree_query_r(handle, tree, g, IndexQuerySendCallback, userdata);
-    }
+    queryResult result = {0};
+    GEOSSTRtree_query_r(handle, tree, g, IndexQueryCallback, &result);
+    *num = result.num;
+    return result.arr;
+}
 */
 import "C"
diff --git a/geom/geos/index.go b/geom/geos/index.go
index 62dd951..4bfc1fa 100644
--- a/geom/geos/index.go
+++ b/geom/geos/index.go
@@ -4,10 +4,11 @@ package geos
 #cgo LDFLAGS: -lgeos_c
 #include "geos_c.h"
 #include <stdlib.h>
+#include <stdint.h>
 
-extern void IndexQuerySendCallback(void *, void *);
+extern void IndexQueryCallback(void *, void *);
 extern void goIndexSendQueryResult(size_t, void *);
-extern void IndexQuery(GEOSContextHandle_t, GEOSSTRtree *, const GEOSGeometry *, void *);
+extern uint32_t *IndexQuery(GEOSContextHandle_t, GEOSSTRtree *, const GEOSGeometry *, uint32_t *);
 extern void IndexAdd(GEOSContextHandle_t, GEOSSTRtree *, const GEOSGeometry *, size_t);
 
 */
@@ -47,23 +48,17 @@ func (this *Geos) IndexAdd(index *Index, geom *Geom) {
 
 // IndexQuery queries the index for intersections with geom.
 func (this *Geos) IndexQuery(index *Index, geom *Geom) []IndexGeom {
-	hits := make(chan int)
-	go func() {
-		// using a pointer to our hits chan to pass it through
-		// C.IndexQuerySendCallback (in C.IndexQuery) back
-		// to goIndexSendQueryResult
-		C.IndexQuery(this.v, index.v, geom.v, unsafe.Pointer(&hits))
-		close(hits)
-	}()
+	var num C.uint32_t
+	r := C.IndexQuery(this.v, index.v, geom.v, &num)
+	if r == nil {
+		return nil
+	}
+	hits := (*[2 << 16]C.uint32_t)(unsafe.Pointer(r))[:num]
+	defer C.free(unsafe.Pointer(r))
+
 	var geoms []IndexGeom
 	for idx := range hits {
 		geoms = append(geoms, index.geoms[idx])
 	}
 	return geoms
 }
-
-//export goIndexSendQueryResult
-func goIndexSendQueryResult(id C.size_t, ptr unsafe.Pointer) {
-	results := *(*chan int)(ptr)
-	results <- int(id)
-}