diff --git a/inject/javax_inject/environment.mk b/inject/javax_inject/environment.mk
index 40a72470a3..97c2d0aa81 100644
--- a/inject/javax_inject/environment.mk
+++ b/inject/javax_inject/environment.mk
@@ -30,7 +30,7 @@ CLASSES_DIR = $(BUILD_DIR)/classes
 INJECT_SRC_JAR = $(JAVA_DEPS_JAR_DIR)/$(JAVAX_INJECT_SOURCE_JAR)
 INJECT_JAR_FULL = $(JAVA_DEPS_JAR_DIR)/$(JAVAX_INJECT_JAR)
 
-OBJCFLAGS := $(CC_WARNINGS) $(DEBUGFLAGS)
+OBJCFLAGS := $(CC_WARNINGS) $(DEBUGFLAGS) -fobjc-weak
 
 # J2ObjC settings
 J2OBJC = $(DIST_DIR)/j2objc -classpath $(INJECT_JAR_FULL) -d $(BUILD_DIR)
diff --git a/jre_emul/Classes/J2ObjC_common.h b/jre_emul/Classes/J2ObjC_common.h
index 0c3d98f71d..9183ec37ca 100644
--- a/jre_emul/Classes/J2ObjC_common.h
+++ b/jre_emul/Classes/J2ObjC_common.h
@@ -124,7 +124,7 @@ __attribute__((always_inline)) inline id JreRetainedAutoreleasedReturnValue(id v
 #if __has_feature(objc_arc_weak)
 # define WEAK_ __weak
 #else
-# define WEAK_ __unsafe_unretained
+# error j2objc requires zeroing Objective-C weak references.
 #endif
 
 CF_EXTERN_C_BEGIN
diff --git a/jre_emul/environment.mk b/jre_emul/environment.mk
index 9941cbce53..ec0b40a2f0 100644
--- a/jre_emul/environment.mk
+++ b/jre_emul/environment.mk
@@ -154,7 +154,7 @@ endif
 
 # The -fobjc flags match XCode (a link fails without them because of
 # missing symbols of the form OBJC_CLASS_$_[classname]).
-OBJCFLAGS += $(WARNINGS) -fno-strict-overflow \
+OBJCFLAGS += $(WARNINGS) -fobjc-weak -fno-strict-overflow \
   -fobjc-abi-version=2 -fobjc-legacy-dispatch $(DEBUGFLAGS) \
   -I/System/Library/Frameworks/ExceptionHandling.framework/Headers \
   -I/System/Library/Frameworks/Security.framework/Headers \
@@ -185,5 +185,5 @@ ifeq ("$(strip $(CLANG_ENABLE_OBJC_ARC))", "YES")
 TRANSLATE_ARGS += -use-arc
 OBJCFLAGS := $(OBJCFLAGS) -fobjc-arc -fobjc-arc-exceptions\
  -Wno-arc-bridge-casts-disallowed-in-nonarc \
- -Xclang -fobjc-runtime-has-weak
+ -Xclang
 endif
diff --git a/junit/environment.mk b/junit/environment.mk
index 3553d4007d..6d00ae754c 100644
--- a/junit/environment.mk
+++ b/junit/environment.mk
@@ -36,7 +36,7 @@ RUNNER_LIB_DIST = $(ARCH_LIB_DIR)/libjunit_runner.a
 
 # The -fobjc flags match XCode (a link fails without them because of
 # missing symbols of the form OBJC_CLASS_$_[classname]).
-OBJCFLAGS := -ObjC $(CC_WARNINGS) \
+OBJCFLAGS := -ObjC $(CC_WARNINGS) -fobjc-weak \
   -fobjc-abi-version=2 -fobjc-legacy-dispatch $(DEBUGFLAGS) \
   -I/System/Library/Frameworks/ExceptionHandling.framework/Headers
 
@@ -47,5 +47,5 @@ ifeq ("$(strip $(CLANG_ENABLE_OBJC_ARC))", "YES")
 J2OBJC := $(J2OBJC) -use-arc
 OBJCFLAGS := $(OBJCFLAGS) -fobjc-arc -fobjc-arc-exceptions\
  -Wno-arc-bridge-casts-disallowed-in-nonarc \
- -Xclang -fobjc-runtime-has-weak
+ -Xclang
 endif