diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index b64895f3..c56b1585 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -40,7 +40,7 @@ jobs:
             build-essential ninja-build wget lsb-release software-properties-common gnupg \
             libgl1-mesa-dev libglew-dev libglfw3-dev \
             libpng-dev libopenal-dev libluajit-5.1-dev \
-            libserialport-dev libsndfile1-dev \
+            libserialport-dev libsndfile1-dev libcurl4-openssl-dev \
             xorg-dev libxkbcommon-dev libwayland-dev wayland-protocols
 
       - name: Install LLVM/Clang 22
diff --git a/.github/workflows/build_bin.yml b/.github/workflows/build_bin.yml
index c64539b5..6ba1a384 100644
--- a/.github/workflows/build_bin.yml
+++ b/.github/workflows/build_bin.yml
@@ -181,6 +181,7 @@ jobs:
             libluajit-5.1-dev \
             libserialport-dev \
             libsndfile1-dev \
+            libcurl4-openssl-dev \
             xorg-dev \
             libxkbcommon-dev \
             libwayland-dev \
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3dc46bbd..7ec662cd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -630,10 +630,18 @@ find_package(Threads REQUIRED)
 target_link_libraries(${PROJECT_NAME} Threads::Threads)
 
 # the editor's map imagery talks to a WMS over https. windows has WinHttp in the platform sdk;
-# everywhere else libcurl is the transport (see editor/orthophoto.cpp)
+# everywhere else libcurl is the transport (see editor/orthophoto.cpp). it is not required: a tree
+# without it builds an editor that draws and exports as usual, only with no imagery behind the plan
 if (NOT WIN32)
-	find_package(CURL REQUIRED)
-	target_link_libraries(${PROJECT_NAME} CURL::libcurl)
+	find_package(CURL)
+	if (CURL_FOUND)
+		target_link_libraries(${PROJECT_NAME} CURL::libcurl)
+		target_compile_definitions(${PROJECT_NAME} PRIVATE WITH_CURL)
+	else()
+		message(WARNING
+			"libcurl not found: the editor will have no map imagery. "
+			"Install libcurl4-openssl-dev (Debian/Ubuntu) or libcurl-devel (Fedora) to get it back.")
+	endif()
 endif()
 
 find_package(GLM REQUIRED)
diff --git a/editor/orthophoto.cpp b/editor/orthophoto.cpp
index f4e650e2..3ba38771 100644
--- a/editor/orthophoto.cpp
+++ b/editor/orthophoto.cpp
@@ -20,7 +20,7 @@ module;
 #include <windows.h>
 #include <winhttp.h>
 #pragma comment(lib, "winhttp.lib")
-#else
+#elif defined(WITH_CURL)
 #include <curl/curl.h>
 #endif
 
@@ -37,6 +37,21 @@ obtain one at
 http://mozilla.org/MPL/2.0/.
 */
 
+namespace
+{
+
+// stb keeps one flip flag for the whole program - there is a single stb_image.c in the build - and
+// the model texture loader turns it on for its own sake (models want the bottom row first). A WMS
+// tile is the other way about: its first row is its northern edge, which is what the drawing code
+// takes v=0 to be. So the orientation is stated per thread, where nobody else can reach it, rather
+// than left to whoever decoded an image last
+void decode_top_down()
+{
+	stbi_set_flip_vertically_on_load_thread(0);
+}
+
+} // namespace
+
 namespace editor
 {
 
@@ -143,7 +158,7 @@ bool http_get(std::string const &Url, std::vector<std::uint8_t> &Bytes, std::str
 	return ok;
 }
 
-#else
+#elif defined(WITH_CURL)
 
 // libcurl's write callback: appends one chunk of the body to the caller's buffer
 std::size_t append_body(char const *Data, std::size_t const Size, std::size_t const Count, void *Userdata)
@@ -205,6 +220,22 @@ bool http_get(std::string const &Url, std::vector<std::uint8_t> &Bytes, std::str
 	return ok;
 }
 
+#else
+
+// built without a transport: libcurl was not there when this was configured. the editor draws and
+// exports as usual - there is simply nothing to put behind the plan, and saying so once is better
+// than a silent grey screen
+bool http_get(std::string const &, std::vector<std::uint8_t> &, std::string &Contenttype)
+{
+	Contenttype.clear();
+	static auto const said = []() {
+		ErrorLog("Editor: built without libcurl, so there is no map imagery");
+		return true;
+	}();
+	(void)said;
+	return false;
+}
+
 #endif
 
 } // namespace
@@ -375,6 +406,7 @@ unsigned int orthophoto_source::upload(editor::plan::TileKey const &Key)
 	int width = 0;
 	int height = 0;
 	int channels = 0;
+	decode_top_down();
 	auto *pixels = stbi_load_from_memory(image->bytes.data(), static_cast<int>(image->bytes.size()), &width, &height, &channels, 3);
 	if (pixels == nullptr)
 	{
@@ -463,6 +495,7 @@ unsigned int upload_image(std::vector<std::uint8_t> const &Bytes)
 	int width = 0;
 	int height = 0;
 	int channels = 0;
+	decode_top_down();
 	auto *pixels = stbi_load_from_memory(Bytes.data(), static_cast<int>(Bytes.size()), &width, &height, &channels, 3);
 	if (pixels == nullptr)
 	{
diff --git a/model/Texture.cpp b/model/Texture.cpp
index c7f65090..e95e6e8a 100644
--- a/model/Texture.cpp
+++ b/model/Texture.cpp
@@ -368,7 +368,10 @@ void opengl_texture::load_PNG()
 void opengl_texture::load_STBI()
 {
 	int x, y, n;
-	stbi_set_flip_vertically_on_load(1);
+	// per thread, not for the whole program: there is one stb_image.c in the build, so the global
+	// flag reaches every other decoder too - which is how the editor's WMS tiles ended up upside
+	// down as soon as any model texture had been loaded through this path
+	stbi_set_flip_vertically_on_load_thread(1);
 	uint8_t *image = stbi_load((name + type).c_str(), &x, &y, &n, 4);
 
 	if (!image) {