diff --git a/mozilla/client.mk b/mozilla/client.mk
index ab7e54cbb99..a1f566fdccc 100644
--- a/mozilla/client.mk
+++ b/mozilla/client.mk
@@ -951,14 +951,14 @@ ifndef MOZ_BUILD_PROJECTS
 # Building a single project, OBJDIR is usable.
 	set -e; \
 	for mkfile in $(MOZ_PREFLIGHT_ALL); do \
-	  $(MAKE) -f $$mkfile preflight_all TOPSRCDIR=$(TOPSRCDIR) OBJDIR=$(OBJDIR) MOZ_OBJDIR=$(MOZ_OBJDIR); \
+	  $(MAKE) -f $(TOPSRCDIR)/$$mkfile preflight_all TOPSRCDIR=$(TOPSRCDIR) OBJDIR=$(OBJDIR) MOZ_OBJDIR=$(MOZ_OBJDIR); \
 	done
 else
 # OBJDIR refers to the project-specific OBJDIR, which is not available at
 # this point when building multiple projects.  Only MOZ_OBJDIR is available.
 	set -e; \
 	for mkfile in $(MOZ_PREFLIGHT_ALL); do \
-	  $(MAKE) -f $$mkfile preflight_all TOPSRCDIR=$(TOPSRCDIR) MOZ_OBJDIR=$(MOZ_OBJDIR) MOZ_BUILD_PROJECTS="$(MOZ_BUILD_PROJECTS)"; \
+	  $(MAKE) -f $(TOPSRCDIR)/$$mkfile preflight_all TOPSRCDIR=$(TOPSRCDIR) MOZ_OBJDIR=$(MOZ_OBJDIR) MOZ_BUILD_PROJECTS="$(MOZ_BUILD_PROJECTS)"; \
 	done
 endif
 endif
@@ -1055,7 +1055,7 @@ build profiledbuild alldep preflight::
 ifdef MOZ_PREFLIGHT
 	set -e; \
 	for mkfile in $(MOZ_PREFLIGHT); do \
-	  $(MAKE) -f $$mkfile preflight TOPSRCDIR=$(TOPSRCDIR) OBJDIR=$(OBJDIR) MOZ_OBJDIR=$(MOZ_OBJDIR); \
+	  $(MAKE) -f $(TOPSRCDIR)/$$mkfile preflight TOPSRCDIR=$(TOPSRCDIR) OBJDIR=$(OBJDIR) MOZ_OBJDIR=$(MOZ_OBJDIR); \
 	done
 endif
 
@@ -1094,7 +1094,7 @@ build profiledbuild alldep postflight::
 ifdef MOZ_POSTFLIGHT
 	set -e; \
 	for mkfile in $(MOZ_POSTFLIGHT); do \
-	  $(MAKE) -f $$mkfile postflight TOPSRCDIR=$(TOPSRCDIR) OBJDIR=$(OBJDIR) MOZ_OBJDIR=$(MOZ_OBJDIR); \
+	  $(MAKE) -f $(TOPSRCDIR)/$$mkfile postflight TOPSRCDIR=$(TOPSRCDIR) OBJDIR=$(OBJDIR) MOZ_OBJDIR=$(MOZ_OBJDIR); \
 	done
 endif
 
@@ -1111,14 +1111,14 @@ ifndef MOZ_BUILD_PROJECTS
 # Building a single project, OBJDIR is usable.
 	set -e; \
 	for mkfile in $(MOZ_POSTFLIGHT_ALL); do \
-	  $(MAKE) -f $$mkfile postflight_all TOPSRCDIR=$(TOPSRCDIR) OBJDIR=$(OBJDIR) MOZ_OBJDIR=$(MOZ_OBJDIR); \
+	  $(MAKE) -f $(TOPSRCDIR)/$$mkfile postflight_all TOPSRCDIR=$(TOPSRCDIR) OBJDIR=$(OBJDIR) MOZ_OBJDIR=$(MOZ_OBJDIR); \
 	done
 else
 # OBJDIR refers to the project-specific OBJDIR, which is not available at
 # this point when building multiple projects.  Only MOZ_OBJDIR is available.
 	set -e; \
 	for mkfile in $(MOZ_POSTFLIGHT_ALL); do \
-	  $(MAKE) -f $$mkfile postflight_all TOPSRCDIR=$(TOPSRCDIR) MOZ_OBJDIR=$(MOZ_OBJDIR) MOZ_BUILD_PROJECTS="$(MOZ_BUILD_PROJECTS)"; \
+	  $(MAKE) -f $(TOPSRCDIR)/$$mkfile postflight_all TOPSRCDIR=$(TOPSRCDIR) MOZ_OBJDIR=$(MOZ_OBJDIR) MOZ_BUILD_PROJECTS="$(MOZ_BUILD_PROJECTS)"; \
 	done
 endif
 endif