diff --git a/configure b/configure
index ad2dd1b87895a..ca5851176ca0d 100755
--- a/configure
+++ b/configure
@@ -418,7 +418,7 @@ opt optimize-llvm 1 "build optimized LLVM"
 opt optimize-tests 1 "build tests with optimizations"
 opt libcpp 1 "build with llvm with libc++ instead of libstdc++ when using clang"
 opt llvm-assertions 1 "build LLVM with assertions"
-opt debug 1 "build with extra debug fun"
+opt debug 0 "build with extra debug fun"
 opt ratchet-bench 0 "ratchet benchmarks"
 opt fast-make 0 "use .gitmodules as timestamp for submodule deps"
 opt manage-submodules 1 "let the build manage the git submodules"
diff --git a/mk/main.mk b/mk/main.mk
index a12198b771b82..3bde0bd2ed0a4 100644
--- a/mk/main.mk
+++ b/mk/main.mk
@@ -105,7 +105,6 @@ CFG_JEMALLOC_FLAGS :=
 ifdef CFG_DISABLE_OPTIMIZE
   $(info cfg: disabling rustc optimization (CFG_DISABLE_OPTIMIZE))
   CFG_RUSTC_FLAGS +=
-  CFG_JEMALLOC_FLAGS += --enable-debug
 else
   # The rtopt cfg turns off runtime sanity checks
   CFG_RUSTC_FLAGS += -O --cfg rtopt
@@ -113,13 +112,14 @@ endif
 
 CFG_JEMALLOC_FLAGS += $(JEMALLOC_FLAGS)
 
-ifdef CFG_DISABLE_DEBUG
+ifndef CFG_ENABLE_DEBUG
   CFG_RUSTC_FLAGS += --cfg ndebug
   CFG_GCCISH_CFLAGS += -DRUST_NDEBUG
 else
   $(info cfg: enabling more debugging (CFG_ENABLE_DEBUG))
   CFG_RUSTC_FLAGS += --cfg debug
   CFG_GCCISH_CFLAGS += -DRUST_DEBUG
+  CFG_JEMALLOC_FLAGS += --enable-debug
 endif
 
 ifdef SAVE_TEMPS