diff --git a/Makefile.am b/Makefile.am
index cc0e76f5..78cd6653 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -24,7 +24,7 @@ OSTREE_GITREV=$(shell if command -v git >/dev/null 2>&1 && test -d $(srcdir)/.gi
 ACLOCAL_AMFLAGS = -I buildutil -I libglnx ${ACLOCAL_FLAGS}
 AM_CPPFLAGS += -DDATADIR='"$(datadir)"' -DLIBEXECDIR='"$(libexecdir)"' \
 	-DLOCALEDIR=\"$(datadir)/locale\" -DSYSCONFDIR=\"$(sysconfdir)\" \
-	-DSHORTENED_SYSCONFDIR=\"$(shortened_sysconfdir)\" \
+	-DTARGET_PREFIX='"$(prefix)"' -DSHORTENED_SYSCONFDIR=\"$(shortened_sysconfdir)\" \
 	-DOSTREE_FEATURES='"$(OSTREE_FEATURES)"' \
 	-DOSTREE_COMPILATION \
 	-DG_LOG_DOMAIN=\"OSTree\" \
diff --git a/src/libostree/ostree-bootloader-grub2.c b/src/libostree/ostree-bootloader-grub2.c
index 6f245fb7..2cd02287 100644
--- a/src/libostree/ostree-bootloader-grub2.c
+++ b/src/libostree/ostree-bootloader-grub2.c
@@ -353,7 +353,7 @@ _ostree_bootloader_grub2_write_config (OstreeBootloader      *bootloader,
         use_system_grub2_mkconfig = FALSE;
     }
   else
-    grub_exec = use_system_grub2_mkconfig ? GRUB2_MKCONFIG_PATH : "/usr/lib/ostree/ostree-grub-generator";
+    grub_exec = use_system_grub2_mkconfig ? GRUB2_MKCONFIG_PATH : TARGET_PREFIX "/lib/ostree/ostree-grub-generator";
 
   if (use_system_grub2_mkconfig && ostree_sysroot_get_booted_deployment (self->sysroot) == NULL
       && g_file_has_parent (self->sysroot->path, NULL))