diff --git a/tests/test_geojson.c b/tests/test_geojson.c
index 081a91e..dc20b8e 100644
--- a/tests/test_geojson.c
+++ b/tests/test_geojson.c
@@ -1028,6 +1028,25 @@ void test_geojson_big_shapes() {
     tg_geom_free(geom2);
 }
 
+void test_geojson_geometrycollection() {
+    struct tg_geom *g1 = tg_parse_wkt("POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))");
+    assert(!tg_geom_error(g1));
+    struct tg_geom *g2 = tg_parse_wkt("POLYGON ((300 100, 400 400, 200 400, 100 200, 300 100))");
+    assert(!tg_geom_error(g2));
+    struct tg_geom *collection = tg_geom_new_geometrycollection((const struct tg_geom*const[]) {g1, g2}, 2);
+    assert(!tg_geom_error(collection));
+    char dst1[1024];
+    char dst2[1024];
+    tg_geom_geojson(tg_geom_geometry_at(collection, 1), dst1, sizeof(dst1));
+    struct tg_geom *g3 = tg_parse_geojson(dst1);
+    tg_geom_geojson(g3, dst2, sizeof(dst2));
+    assert(strcmp(dst1, dst2) == 0);
+    tg_geom_free(g1);
+    tg_geom_free(g2);
+    tg_geom_free(collection);
+    tg_geom_free(g3);
+}
+
 int main(int argc, char **argv) {
     seedrand();
     do_test(test_geojson_basic_syntax);
@@ -1035,5 +1054,6 @@ int main(int argc, char **argv) {
     do_test(test_geojson_various);
     do_test(test_geojson_big_shapes);
     do_chaos_test(test_geojson_chaos);
+    do_test(test_geojson_geometrycollection);
     return 0;
 }
diff --git a/tests/test_wkb.c b/tests/test_wkb.c
index c3dc372..98b6f62 100644
--- a/tests/test_wkb.c
+++ b/tests/test_wkb.c
@@ -801,6 +801,26 @@ void test_wkb_big_shapes() {
     tg_geom_free(geom2);
 }
 
+void test_wkb_geometrycollection() {
+    struct tg_geom *g1 = tg_parse_wkt("POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))");
+    assert(!tg_geom_error(g1));
+    struct tg_geom *g2 = tg_parse_wkt("POLYGON ((300 100, 400 400, 200 400, 100 200, 300 100))");
+    assert(!tg_geom_error(g2));
+    struct tg_geom *collection = tg_geom_new_geometrycollection((const struct tg_geom*const[]) {g1, g2}, 2);
+    assert(!tg_geom_error(collection));
+    uint8_t dst1[1024];
+    uint8_t dst2[1024];
+    size_t sz1 = tg_geom_wkb(tg_geom_geometry_at(collection, 1), dst1, sizeof(dst1));
+    struct tg_geom *g3 = tg_parse_wkb(dst1, sz1);
+    size_t sz2 = tg_geom_wkb(g3, dst2, sizeof(dst2));
+    assert(sz1 == sz2 && memcmp(dst1, dst2, sz1) == 0);
+    tg_geom_free(g1);
+    tg_geom_free(g2);
+    tg_geom_free(collection);
+    tg_geom_free(g3);
+}
+
+
 int main(int argc, char **argv) {
     do_test(test_wkb_basic_syntax);
     do_test(test_wkb_max_depth);
@@ -810,5 +830,6 @@ int main(int argc, char **argv) {
     do_test(test_wkb_with_srid);
     do_test(test_wkb_various);
     do_test(test_wkb_big_shapes);
+    do_test(test_wkb_geometrycollection);
     return 0;
 }
diff --git a/tests/test_wkt.c b/tests/test_wkt.c
index cfe58bf..0fa4fe6 100644
--- a/tests/test_wkt.c
+++ b/tests/test_wkt.c
@@ -715,6 +715,24 @@ void test_wkt_various() {
     tg_geom_free(geom);
 }
 
+void test_wkt_geometrycollection() {
+    struct tg_geom *g1 = tg_parse_wkt("POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10))");
+    assert(!tg_geom_error(g1));
+    struct tg_geom *g2 = tg_parse_wkt("POLYGON ((300 100, 400 400, 200 400, 100 200, 300 100))");
+    assert(!tg_geom_error(g2));
+    struct tg_geom *collection = tg_geom_new_geometrycollection((const struct tg_geom*const[]) {g1, g2}, 2);
+    assert(!tg_geom_error(collection));
+    char dst1[1024];
+    char dst2[1024];
+    tg_geom_wkt(tg_geom_geometry_at(collection, 1), dst1, sizeof(dst1));
+    struct tg_geom *g3 = tg_parse_wkt(dst1);
+    tg_geom_wkt(g3, dst2, sizeof(dst2));
+    assert(strcmp(dst1, dst2) == 0);
+    tg_geom_free(g1);
+    tg_geom_free(g2);
+    tg_geom_free(collection);
+    tg_geom_free(g3);
+}
 
 int main(int argc, char **argv) {
     seedrand();
@@ -722,5 +740,6 @@ int main(int argc, char **argv) {
     do_test(test_wkt_max_depth);
     do_chaos_test(test_wkt_chaos);
     do_test(test_wkt_various);
+    do_test(test_wkt_geometrycollection);
     return 0;
 }
diff --git a/tg.c b/tg.c
index fd55cdd..026c1da 100644
--- a/tg.c
+++ b/tg.c
@@ -10600,7 +10600,9 @@ static void write_geom_geometrycollection_geojson(const struct tg_geom *geom,
     write_char(wr, '}');
 }
 
-static void write_geom_geojson(const struct tg_geom *geom, struct writer *wr) {
+static void write_base_geom_geojson(const struct tg_geom *geom,
+    struct writer *wr)
+{
     if ((geom->head.flags&IS_ERROR) == IS_ERROR) {
         // sigh, just write us an empty point ...
         write_string(wr, "{\"type\":\"Point\",\"coordinates\":[]}");
@@ -10775,6 +10777,26 @@ static void write_poly_geojson(const struct tg_poly *poly, struct writer *wr) {
     }
 }
 
+static void write_geom_geojson(const struct tg_geom *geom, struct writer *wr) {
+    switch (geom->head.base) {
+    case BASE_GEOM:
+        write_base_geom_geojson(geom, wr);
+        break;
+    case BASE_POINT:
+        write_point_geojson((struct boxed_point*)geom, wr);
+        break;
+    case BASE_LINE:
+        write_line_geojson((struct tg_line*)geom, wr);
+        break;
+    case BASE_RING:
+        write_ring_geojson((struct tg_ring*)geom, wr);
+        break;
+    case BASE_POLY:
+        write_poly_geojson((struct tg_poly*)geom, wr);
+        break;
+    }
+}
+
 /// Writes a GeoJSON representation of a geometry.
 ///
 /// The content is stored as a C string in the buffer pointed to by dst.
@@ -10804,23 +10826,7 @@ static void write_poly_geojson(const struct tg_poly *poly, struct writer *wr) {
 size_t tg_geom_geojson(const struct tg_geom *geom, char *dst, size_t n) {
     if (!geom) return 0;
     struct writer wr = { .dst = (uint8_t*)dst, .n = n };
-    switch (geom->head.base) {
-    case BASE_GEOM:
-        write_geom_geojson(geom, &wr);
-        break;
-    case BASE_POINT:
-        write_point_geojson((struct boxed_point*)geom, &wr);
-        break;
-    case BASE_LINE:
-        write_line_geojson((struct tg_line*)geom, &wr);
-        break;
-    case BASE_RING:
-        write_ring_geojson((struct tg_ring*)geom, &wr);
-        break;
-    case BASE_POLY:
-        write_poly_geojson((struct tg_poly*)geom, &wr);
-        break;
-    }
+    write_geom_geojson(geom, &wr);
     write_nullterm(&wr);
     return wr.count;
 }
@@ -12129,7 +12135,7 @@ static void write_geom_geometrycollection_wkt(const struct tg_geom *geom,
     write_char(wr, ')');
 }
 
-static void write_geom_wkt(const struct tg_geom *geom, struct writer *wr) {
+static void write_base_geom_wkt(const struct tg_geom *geom, struct writer *wr) {
     switch (geom->head.type) {
     case TG_POINT:
         write_geom_point_wkt(geom, wr);
@@ -12155,6 +12161,26 @@ static void write_geom_wkt(const struct tg_geom *geom, struct writer *wr) {
     }
 }
 
+static void write_geom_wkt(const struct tg_geom *geom, struct writer *wr) {
+    switch (geom->head.base) {
+    case BASE_GEOM:
+        write_base_geom_wkt(geom, wr);
+        break;
+    case BASE_POINT:
+        write_point_wkt((struct boxed_point*)geom, wr);
+        break;
+    case BASE_LINE:
+        write_line_wkt((struct tg_line*)geom, wr);
+        break;
+    case BASE_RING:
+        write_ring_wkt((struct tg_ring*)geom, wr);
+        break;
+    case BASE_POLY:
+        write_poly_wkt((struct tg_poly*)geom, wr);
+        break;
+    }
+}
+
 /// Writes a Well-known text (WKT) representation of a geometry.
 ///
 /// The content is stored as a C string in the buffer pointed to by dst.
@@ -12184,23 +12210,7 @@ static void write_geom_wkt(const struct tg_geom *geom, struct writer *wr) {
 size_t tg_geom_wkt(const struct tg_geom *geom, char *dst, size_t n) {
     if (!geom) return 0;
     struct writer wr = { .dst = (uint8_t*)dst, .n = n };
-    switch (geom->head.base) {
-    case BASE_GEOM:
-        write_geom_wkt(geom, &wr);
-        break;
-    case BASE_POINT:
-        write_point_wkt((struct boxed_point*)geom, &wr);
-        break;
-    case BASE_LINE:
-        write_line_wkt((struct tg_line*)geom, &wr);
-        break;
-    case BASE_RING:
-        write_ring_wkt((struct tg_ring*)geom, &wr);
-        break;
-    case BASE_POLY:
-        write_poly_wkt((struct tg_poly*)geom, &wr);
-        break;
-    }
+    write_geom_wkt(geom, &wr);
     write_nullterm(&wr);
     return wr.count;
 }
@@ -13284,7 +13294,7 @@ static void write_geom_geometrycollection_wkb(const struct tg_geom *geom,
     }
 }
 
-static void write_geom_wkb(const struct tg_geom *geom, struct writer *wr) {
+static void write_base_geom_wkb(const struct tg_geom *geom, struct writer *wr) {
     switch (geom->head.type) {
     case TG_POINT:
         write_geom_point_wkb(geom, wr);
@@ -13310,6 +13320,26 @@ static void write_geom_wkb(const struct tg_geom *geom, struct writer *wr) {
     }
 }
 
+static void write_geom_wkb(const struct tg_geom *geom, struct writer *wr) {
+    switch (geom->head.base) {
+    case BASE_GEOM:
+        write_base_geom_wkb(geom, wr);
+        break;
+    case BASE_POINT:
+        write_point_wkb((struct boxed_point*)geom, wr);
+        break;
+    case BASE_LINE:
+        write_line_wkb((struct tg_line*)geom, wr);
+        break;
+    case BASE_RING:
+        write_ring_wkb((struct tg_ring*)geom, wr);
+        break;
+    case BASE_POLY:
+        write_poly_wkb((struct tg_poly*)geom, wr);
+        break;
+    }
+}
+
 /// Writes a Well-known binary (WKB) representation of a geometry.
 ///
 /// The content is stored in the buffer pointed by dst.
@@ -13337,23 +13367,7 @@ static void write_geom_wkb(const struct tg_geom *geom, struct writer *wr) {
 size_t tg_geom_wkb(const struct tg_geom *geom, uint8_t *dst, size_t n) {
     if (!geom) return 0;
     struct writer wr = { .dst = dst, .n = n };
-    switch (geom->head.base) {
-    case BASE_GEOM:
-        write_geom_wkb(geom, &wr);
-        break;
-    case BASE_POINT:
-        write_point_wkb((struct boxed_point*)geom, &wr);
-        break;
-    case BASE_LINE:
-        write_line_wkb((struct tg_line*)geom, &wr);
-        break;
-    case BASE_RING:
-        write_ring_wkb((struct tg_ring*)geom, &wr);
-        break;
-    case BASE_POLY:
-        write_poly_wkb((struct tg_poly*)geom, &wr);
-        break;
-    }
+    write_geom_wkb(geom, &wr);
     return wr.count;
 }