diff --git a/.gitignore b/.gitignore
index 26219627a..6eca1307e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -46,6 +46,7 @@ duplicates.txt
 /infer/tests/build_systems/diff_*/src
 /infer/tests/build_systems/differential_*/**/*.class
 /infer/tests/build_systems/differential_*/**/Diff*.java
+/infer/tests/build_systems/differential_*/**/Diff*.m
 /infer/tests/build_systems/incremental_analysis_remove_file/src
 /infer/tests/build_systems/incremental_analysis_cost_change/src
 /infer/tests/build_systems/incremental_analysis_add_procedure/src
diff --git a/infer/tests/build_systems/differential_of_costs_report_java/Makefile b/infer/tests/build_systems/differential_of_costs_report_java/Makefile
index 1727936bd..2d0316125 100644
--- a/infer/tests/build_systems/differential_of_costs_report_java/Makefile
+++ b/infer/tests/build_systems/differential_of_costs_report_java/Makefile
@@ -6,8 +6,9 @@
 # E2E test for differential of costs
 
 TESTS_DIR = ../..
-SOURCES = src/DiffExample.java.current src/DiffExample.java.previous src/DiffExampleUIThread.java.current src/DiffExampleUIThread.java.previous
-CLEAN_EXTRA = src/Diff*.java *.class
+SOURCES = src/DiffExample.current.java src/DiffExample.previous.java src/DiffExampleUIThread.current.java src/DiffExampleUIThread.previous.java
+COPIED = src/DiffExample.java src/DiffExampleUIThread.java
+CLEAN_EXTRA = $(COPIED) *.class
 include $(TESTS_DIR)/differential.make
 include $(TESTS_DIR)/java.make
 INFERPRINT_ISSUES_FIELDS = \
@@ -16,13 +17,13 @@ INFERPRINT_ISSUES_FIELDS = \
 $(CURRENT_REPORT) $(PREVIOUS_REPORT): $(JAVA_DEPS)
 
 $(CURRENT_REPORT):
-	$(QUIET)$(COPY) src/DiffExample.java.current src/DiffExample.java
-	$(QUIET)$(COPY) src/DiffExampleUIThread.java.current src/DiffExampleUIThread.java
+	$(QUIET)$(COPY) src/DiffExample.current.java src/DiffExample.java
+	$(QUIET)$(COPY) src/DiffExampleUIThread.current.java src/DiffExampleUIThread.java
 	$(QUIET)$(call silent_on_success,Testing Cost Differential: current,\
-	$(INFER_BIN) --no-filtering --cost-only -o $(CURRENT_DIR) -- $(JAVAC) -cp $(CLASSPATH)  src/*.java)
+	$(INFER_BIN) --no-filtering --cost-only -o $(CURRENT_DIR) -- $(JAVAC) -cp $(CLASSPATH)  $(COPIED))
 
 $(PREVIOUS_REPORT):
-	$(QUIET)$(COPY) src/DiffExample.java.previous src/DiffExample.java
-	$(QUIET)$(COPY) src/DiffExampleUIThread.java.previous src/DiffExampleUIThread.java
+	$(QUIET)$(COPY) src/DiffExample.previous.java src/DiffExample.java
+	$(QUIET)$(COPY) src/DiffExampleUIThread.previous.java src/DiffExampleUIThread.java
 	$(QUIET)$(call silent_on_success,Testing Cost Differential: previous,\
-	$(INFER_BIN) --debug --no-filtering --cost-only -o $(PREVIOUS_DIR) -- $(JAVAC)  -cp $(CLASSPATH) src/*.java)
+	$(INFER_BIN) --debug --no-filtering --cost-only -o $(PREVIOUS_DIR) -- $(JAVAC) -cp $(CLASSPATH) $(COPIED))
diff --git a/infer/tests/build_systems/differential_of_costs_report_java/src/DiffExample.java.current b/infer/tests/build_systems/differential_of_costs_report_java/src/DiffExample.current.java
similarity index 100%
rename from infer/tests/build_systems/differential_of_costs_report_java/src/DiffExample.java.current
rename to infer/tests/build_systems/differential_of_costs_report_java/src/DiffExample.current.java
diff --git a/infer/tests/build_systems/differential_of_costs_report_java/src/DiffExample.java.previous b/infer/tests/build_systems/differential_of_costs_report_java/src/DiffExample.previous.java
similarity index 100%
rename from infer/tests/build_systems/differential_of_costs_report_java/src/DiffExample.java.previous
rename to infer/tests/build_systems/differential_of_costs_report_java/src/DiffExample.previous.java
diff --git a/infer/tests/build_systems/differential_of_costs_report_java/src/DiffExampleUIThread.java.current b/infer/tests/build_systems/differential_of_costs_report_java/src/DiffExampleUIThread.current.java
similarity index 99%
rename from infer/tests/build_systems/differential_of_costs_report_java/src/DiffExampleUIThread.java.current
rename to infer/tests/build_systems/differential_of_costs_report_java/src/DiffExampleUIThread.current.java
index f89e6756e..2461d037e 100644
--- a/infer/tests/build_systems/differential_of_costs_report_java/src/DiffExampleUIThread.java.current
+++ b/infer/tests/build_systems/differential_of_costs_report_java/src/DiffExampleUIThread.current.java
@@ -33,4 +33,4 @@ public class DiffExampleUIThread {
    f1(x);
 }
 
-}
\ No newline at end of file
+}
diff --git a/infer/tests/build_systems/differential_of_costs_report_java/src/DiffExampleUIThread.java.previous b/infer/tests/build_systems/differential_of_costs_report_java/src/DiffExampleUIThread.previous.java
similarity index 99%
rename from infer/tests/build_systems/differential_of_costs_report_java/src/DiffExampleUIThread.java.previous
rename to infer/tests/build_systems/differential_of_costs_report_java/src/DiffExampleUIThread.previous.java
index 05e642909..0f429287d 100644
--- a/infer/tests/build_systems/differential_of_costs_report_java/src/DiffExampleUIThread.java.previous
+++ b/infer/tests/build_systems/differential_of_costs_report_java/src/DiffExampleUIThread.previous.java
@@ -33,4 +33,4 @@ public class DiffExampleUIThread {
    return f2(x);
 }
 
-}
\ No newline at end of file
+}
diff --git a/infer/tests/build_systems/differential_of_costs_report_objc/Makefile b/infer/tests/build_systems/differential_of_costs_report_objc/Makefile
index 907e9b54a..a254afbd8 100644
--- a/infer/tests/build_systems/differential_of_costs_report_objc/Makefile
+++ b/infer/tests/build_systems/differential_of_costs_report_objc/Makefile
@@ -6,7 +6,9 @@
 # E2E test for differential of costs
 
 TESTS_DIR = ../..
-SOURCES = src/DiffBlock.m.current src/DiffBlock.m.previous
+SOURCES = src/DiffBlock.current.m src/DiffBlock.previous.m
+COPIED = src/DiffBlock.m
+CLEAN_EXTRA = $(COPIED)
 CLANG_OPTIONS = -c $(OBJC_CLANG_OPTIONS)
 include $(TESTS_DIR)/differential.make
 include $(TESTS_DIR)/objc.make
@@ -16,11 +18,11 @@ INFERPRINT_ISSUES_FIELDS = \
 $(CURRENT_REPORT) $(PREVIOUS_REPORT): $(OBJC_DEPS)
 
 $(CURRENT_REPORT):
-	$(QUIET)$(COPY) src/DiffBlock.m.current src/DiffBlock.m
+	$(QUIET)$(COPY) src/DiffBlock.current.m src/DiffBlock.m
 	$(QUIET)$(call silent_on_success,Testing Cost Differential: current,\
-	$(INFER_BIN)  --no-filtering --cost-only -o $(CURRENT_DIR) -- clang $(CLANG_OPTIONS) src/*.m)
+	$(INFER_BIN)  --no-filtering --cost-only -o $(CURRENT_DIR) -- clang $(CLANG_OPTIONS) $(COPIED))
 
 $(PREVIOUS_REPORT):
-	$(QUIET)$(COPY) src/DiffBlock.m.previous src/DiffBlock.m
+	$(QUIET)$(COPY) src/DiffBlock.previous.m src/DiffBlock.m
 	$(QUIET)$(call silent_on_success,Testing Cost Differential: previous,\
-	$(INFER_BIN) --debug --no-filtering --cost-only -o $(PREVIOUS_DIR) -- clang $(CLANG_OPTIONS) src/*.m)
+	$(INFER_BIN) --debug --no-filtering --cost-only -o $(PREVIOUS_DIR) -- clang $(CLANG_OPTIONS) $(COPIED))
diff --git a/infer/tests/build_systems/differential_of_costs_report_objc/src/DiffBlock.m.current b/infer/tests/build_systems/differential_of_costs_report_objc/src/DiffBlock.current.m
similarity index 100%
rename from infer/tests/build_systems/differential_of_costs_report_objc/src/DiffBlock.m.current
rename to infer/tests/build_systems/differential_of_costs_report_objc/src/DiffBlock.current.m
diff --git a/infer/tests/build_systems/differential_of_costs_report_objc/src/DiffBlock.m.previous b/infer/tests/build_systems/differential_of_costs_report_objc/src/DiffBlock.m.previous
deleted file mode 100644
index c4ec0c836..000000000
--- a/infer/tests/build_systems/differential_of_costs_report_objc/src/DiffBlock.m.previous
+++ /dev/null
@@ -1,51 +0,0 @@
-/*
- * Copyright (c) Facebook, Inc. and its affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-#import <Foundation/Foundation.h>
-
-@interface CallBlocks : NSObject
-
-- (void)take_two_blocks:(NSInteger*)n
-                 block1:(void (^)(NSInteger*))block1
-                 block2:(void (^)(NSInteger*))block2;
-
-@end
-
-@implementation CallBlocks
-
-- (id)init {
-  return self;
-}
-
-- (void)take_two_blocks:(NSInteger*)n
-                 block1:(void (^)(NSInteger*))block1
-                 block2:(void (^)(NSInteger*))block2 {
-  block1(n);
-  block2(n);
-}
-
-@end
-
-@interface Handler : NSObject
-@end
-
-@implementation Handler
-
-- (void (^)(NSString*))func_linear {
-  return ^(NSString* str) {
-    NSLog(@"Report error : %@ \n", str);
-  };
-}
-
-- (void)func_linear:(NSArray*)array {
-  for (id value in array) {
-  }
-}
-
-@end
-
-int main() { return 0; }
diff --git a/infer/tests/build_systems/differential_of_costs_report_objc/src/DiffBlock.m b/infer/tests/build_systems/differential_of_costs_report_objc/src/DiffBlock.previous.m
similarity index 100%
rename from infer/tests/build_systems/differential_of_costs_report_objc/src/DiffBlock.m
rename to infer/tests/build_systems/differential_of_costs_report_objc/src/DiffBlock.previous.m