diff --git a/bootstrap b/bootstrap
index bc08b8dc..c621b77c 100755
--- a/bootstrap
+++ b/bootstrap
@@ -22,6 +22,11 @@ clone_repo_commit() {
         if ! git -C $2 checkout $3; then
             rm -rf $2
         fi
+    else
+        if [ -d $2 ]; then
+            echo "error: '$2' is not a Git repository"
+            exit 1
+        fi
     fi
     if ! [ -d $2 ]; then
         git clone $1 $2
@@ -29,30 +34,32 @@ clone_repo_commit() {
     fi
 }
 
-clone_repo_commit https://github.com/mintsuki/freestanding-toolchain.git build-aux/freestanding-toolchain $FREESTANDING_TOOLCHAIN_COMMIT_HASH
-clone_repo_commit https://github.com/mintsuki/freestanding-headers.git freestanding-headers $FREESTANDING_HEADERS_COMMIT_HASH
+if ! [ -f version ]; then
+    clone_repo_commit https://github.com/mintsuki/freestanding-toolchain.git build-aux/freestanding-toolchain $FREESTANDING_TOOLCHAIN_COMMIT_HASH
+    clone_repo_commit https://github.com/mintsuki/freestanding-headers.git freestanding-headers $FREESTANDING_HEADERS_COMMIT_HASH
 
-clone_repo_commit https://github.com/mintsuki/cc-runtime.git decompressor/cc-runtime $CC_RUNTIME_COMMIT_HASH
-rm -rf common/cc-runtime
-cp -rp decompressor/cc-runtime common/
-for f in common/cc-runtime/*.c; do
-    mv "$f" "$(echo "$f" | sed 's/\.c/.s2.c/g')"
-done
+    clone_repo_commit https://github.com/mintsuki/cc-runtime.git decompressor/cc-runtime $CC_RUNTIME_COMMIT_HASH
+    rm -rf common/cc-runtime
+    cp -rp decompressor/cc-runtime common/
+    for f in common/cc-runtime/*.c; do
+        mv "$f" "$(echo "$f" | sed 's/\.c/.s2.c/g')"
+    done
 
-clone_repo_commit https://github.com/limine-bootloader/limine-efi.git limine-efi $LIMINE_EFI_COMMIT_HASH
+    clone_repo_commit https://github.com/limine-bootloader/limine-efi.git limine-efi $LIMINE_EFI_COMMIT_HASH
 
-clone_repo_commit https://github.com/jibsen/tinf.git tinf $TINF_COMMIT_HASH
-mkdir -p decompressor/tinf
-cp tinf/src/tinf.h tinf/src/tinflate.c tinf/src/tinfgzip.c decompressor/tinf/
-patch -p0 < decompressor/tinf.patch
-rm -f tinf/src/tinf.h.orig tinf/src/tinflate.c.orig tinf/src/tinfgzip.c.orig
+    clone_repo_commit https://github.com/jibsen/tinf.git tinf $TINF_COMMIT_HASH
+    mkdir -p decompressor/tinf
+    cp tinf/src/tinf.h tinf/src/tinflate.c tinf/src/tinfgzip.c decompressor/tinf/
+    patch -p0 < decompressor/tinf.patch
+    rm -f tinf/src/tinf.h.orig tinf/src/tinflate.c.orig tinf/src/tinfgzip.c.orig
 
-clone_repo_commit https://github.com/mintsuki/flanterm.git common/flanterm $FLANTERM_COMMIT_HASH
+    clone_repo_commit https://github.com/mintsuki/flanterm.git common/flanterm $FLANTERM_COMMIT_HASH
 
-clone_repo_commit https://github.com/nothings/stb.git stb $STB_COMMIT_HASH
-cp stb/stb_image.h common/lib/
-patch -p0 < common/stb_image.patch
-rm -f common/lib/stb_image.h.orig
+    clone_repo_commit https://github.com/nothings/stb.git stb $STB_COMMIT_HASH
+    cp stb/stb_image.h common/lib/
+    patch -p0 < common/stb_image.patch
+    rm -f common/lib/stb_image.h.orig
+fi
 
 autoreconf -fvi -Wall
 
@@ -61,7 +68,13 @@ autoreconf -fvi -Wall
 # case and work around...
 for auxfile in config.guess config.sub install-sh; do
     if ! [ -f build-aux/$auxfile ]; then
+        if ! automake --print-libdir >/dev/null 2>&1; then
+            echo "error: Broken autoreconf detected, but missing or broken automake."
+            echo "       Please make sure automake is installed and working."
+            exit 1
+        fi
         mkdir -p build-aux
         cp -v "$(automake --print-libdir)/$auxfile" build-aux/
+        chmod +x build-aux/$auxfile
     fi
 done