diff --git a/libs/gfx/source/program.cpp b/libs/gfx/source/program.cpp
index 65e16431..9c533803 100644
--- a/libs/gfx/source/program.cpp
+++ b/libs/gfx/source/program.cpp
@@ -5,6 +5,7 @@
 
 #include <memory>
 #include <vector>
+#include <sstream>
 
 namespace psemek::gfx
 {
@@ -209,6 +210,32 @@ namespace psemek::gfx
 		gl::Uniform2f(location_, i.min, i.max);
 	}
 
+	static std::string annotated_source(std::string_view source)
+	{
+		std::ostringstream os;
+
+		bool first = true;
+
+		int line = 0;
+		for (char c : source)
+		{
+			if (first)
+			{
+				os << line << ": ";
+				first = false;
+			}
+
+			os.put(c);
+			if (c == '\n')
+			{
+				++line;
+				first = true;
+			}
+		}
+
+		return os.str();
+	}
+
 	static void load_shader(GLuint shader, std::string_view source)
 	{
 		char const * vert_sources[1] { source.data() };
@@ -224,7 +251,7 @@ namespace psemek::gfx
 			gl::GetShaderiv(shader, gl::INFO_LOG_LENGTH, &log_len);
 			std::unique_ptr<char[]> log(new char [log_len]);
 			gl::GetShaderInfoLog(shader, log_len, nullptr, log.get());
-			throw std::runtime_error(util::to_string("Shader compilation failed: ", log.get(), "\nShader source: \n", source));
+			throw std::runtime_error(util::to_string("Shader compilation failed: ", log.get(), "\nShader source: \n", annotated_source(source)));
 		}
 	}