diff --git a/CMakeLists.txt b/CMakeLists.txt
index e3762ee..e5ba873 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -49,6 +49,8 @@ if(MSVC)
     # they have their own __inline; this breaks `static inline` functions.
     # We do not want to care and so we fix this with a definition.
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /Dinline=__inline")
+    # Same for the (C99) __func__ special variable; we use it only in C++ code.
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /D__func__=__FUNCTION__")
 endif()
 
 if(CMAKE_CXX_COMPILER_ID STREQUAL GNU)
diff --git a/src/platform/unixutil.cpp b/src/platform/unixutil.cpp
index 83c0774..ef1a86a 100644
--- a/src/platform/unixutil.cpp
+++ b/src/platform/unixutil.cpp
@@ -8,6 +8,7 @@
 // Copyright 2013 Daniel Richard G. <skunk@iSKUNK.ORG>
 //-----------------------------------------------------------------------------
 #include <time.h>
+#include <execinfo.h>
 
 #include "solvespace.h"
 
@@ -25,6 +26,29 @@ void dbp(const char *str, ...)
     fputc('\n', stderr);
 }
 
+void assert_failure(const char *file, unsigned line, const char *function,
+                    const char *condition, const char *message) {
+    fprintf(stderr, "File %s, line %u, function %s:\n", file, line, function);
+    fprintf(stderr, "Assertion '%s' failed: ((%s) == false).\n", message, condition);
+
+    static void *ptrs[1024] = {};
+    size_t nptrs = backtrace(ptrs, sizeof(ptrs) / sizeof(ptrs[0]));
+    char **syms = backtrace_symbols(ptrs, nptrs);
+
+    fprintf(stderr, "Backtrace:\n");
+    if(syms != NULL) {
+        for(size_t i = 0; i < nptrs; i++) {
+            fprintf(stderr, "%2zu: %s\n", i, syms[i]);
+        }
+    } else {
+        for(size_t i = 0; i < nptrs; i++) {
+            fprintf(stderr, "%2zu: %p\n", i, ptrs[i]);
+        }
+    }
+
+    abort();
+}
+
 FILE *ssfopen(const std::string &filename, const char *mode)
 {
     if(filename.length() != strlen(filename.c_str())) oops();
diff --git a/src/platform/w32util.cpp b/src/platform/w32util.cpp
index 20f3ec6..588e04d 100644
--- a/src/platform/w32util.cpp
+++ b/src/platform/w32util.cpp
@@ -24,6 +24,17 @@ void dbp(const char *str, ...)
     OutputDebugStringA(buf);
 }
 
+void assert_failure(const char *file, unsigned line, const char *function,
+                    const char *condition, const char *message) {
+    dbp("File %s, line %u, function %s:\n", file, line, function);
+    dbp("Assertion '%s' failed: ((%s) == false).\n", message, condition);
+#ifdef NDEBUG
+    _exit(1);
+#else
+    abort();
+#endif
+}
+
 std::string Narrow(const wchar_t *in)
 {
     std::string out;
diff --git a/src/solvespace.h b/src/solvespace.h
index 1e7d306..40fe7cf 100644
--- a/src/solvespace.h
+++ b/src/solvespace.h
@@ -56,14 +56,26 @@ struct FT_FaceRec_;
 #endif
 
 // Debugging functions
-#ifdef NDEBUG
-#define oops() do { dbp("oops at line %d, file %s\n", __LINE__, __FILE__); \
-                    exit(-1); } while(0)
+#if defined(__GNUC__)
+#define ssassert(condition, message) \
+    do { \
+        if(__builtin_expect((condition), true) == false) { \
+            SolveSpace::assert_failure(__FILE__, __LINE__, __func__, #condition, message); \
+            __builtin_unreachable(); \
+        } \
+    } while(0)
 #else
-#define oops() do { dbp("oops at line %d, file %s\n", __LINE__, __FILE__); \
-                    abort(); } while(0)
+#define ssassert(condition, message) \
+    do { \
+        if((condition) == false) { \
+            SolveSpace::assert_failure(__FILE__, __LINE__, __func__, #condition, message); \
+            abort(); \
+        } \
+    } while(0)
 #endif
 
+#define oops() ssassert(false, "oops() called")
+
 #ifndef isnan
 #   define isnan(x) (((x) != (x)) || (x > 1e11) || (x < -1e11))
 #endif
@@ -74,6 +86,12 @@ using std::min;
 using std::max;
 using std::swap;
 
+#if defined(__GNUC__)
+__attribute__((noreturn))
+#endif
+void assert_failure(const char *file, unsigned line, const char *function,
+                    const char *condition, const char *message);
+
 #if defined(__GNUC__)
 __attribute__((__format__ (__printf__, 1, 2)))
 #endif