diff --git a/CMakeLists.txt b/CMakeLists.txt
index 405343e50..a5d6526a2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -94,6 +94,10 @@ ADD_DEFINITIONS(-D_UNICODE=1
 # This defines the FBVF variable.
 INCLUDE(Version)
 
+# Let fish pick up when we're running out of the build directory without installing
+ADD_DEFINITIONS(-DCMAKE_BINARY_DIR="${CMAKE_BINARY_DIR}")
+ADD_DEFINITIONS(-DCMAKE_SOURCE_DIR="${CMAKE_SOURCE_DIR}")
+
 # Teach fish_version.o to rebuild when FBVF changes.
 # The standard C++ include detection machinery misses this.
 SET_SOURCE_FILES_PROPERTIES(src/fish_version.cpp
diff --git a/src/fish.cpp b/src/fish.cpp
index de90cd2a3..1746aed50 100644
--- a/src/fish.cpp
+++ b/src/fish.cpp
@@ -95,6 +95,20 @@ static struct config_paths_t determine_config_directory_paths(const char *argv0)
     std::string exec_path = get_executable_path(argv0);
     if (get_realpath(exec_path)) {
         debug(2, L"exec_path: '%s'", exec_path.c_str());
+
+#ifdef CMAKE_BINARY_DIR
+        // Detect if we're running right out of the CMAKE build directory
+        if (exec_path == std::string(CMAKE_BINARY_DIR) + "/fish") {
+            debug(2, "Running out of build directory, falling back to source paths");
+
+            done = true;
+            paths.data = wcstring{L"" CMAKE_SOURCE_DIR} + L"/share";
+            paths.sysconf = L"" SYSCONFDIR "/fish";
+            paths.doc = L"" DOCDIR;
+            paths.bin = L"" BINDIR;
+        }
+#endif
+
         if (!done) {
             // The next check is that we are in a reloctable directory tree
             const char *installed_suffix = "/bin/fish";