diff --git a/src/libnnp/makefile b/src/libnnp/makefile
index 813e918c7..fea67d54e 100644
--- a/src/libnnp/makefile
+++ b/src/libnnp/makefile
@@ -72,11 +72,11 @@ headers: version
 
 version:
 	@$(eval GIT_VERSION = $(shell git describe --tags --always))
-	@sed -i.bak -E "s/(N2P2_GIT_VERSION) .*/\1 \"$(GIT_VERSION)\"/" version.h
+	@sed -i.bak -E "s?(N2P2_GIT_VERSION) .*?\1 \"$(GIT_VERSION)\"?" version.h
 	@$(eval GIT_REV = $(shell git rev-parse HEAD))
-	@sed -i.bak -E "s/(N2P2_GIT_REV) .*/\1 \"$(GIT_REV)\"/" version.h
+	@sed -i.bak -E "s?(N2P2_GIT_REV) .*?\1 \"$(GIT_REV)\"?" version.h
 	@$(eval GIT_BRANCH = $(shell git rev-parse --abbrev-ref HEAD))
-	@sed -i.bak -E "s/(N2P2_GIT_BRANCH) .*/\1 \"$(GIT_BRANCH)\"/" version.h
+	@sed -i.bak -E "s?(N2P2_GIT_BRANCH) .*?\1 \"$(GIT_BRANCH)\"?" version.h
 	@rm version.h.bak
 
 $(LIB).so: CFLAGS+= -fPIC
@@ -97,9 +97,9 @@ clean: clean-version clean-headers
 	$(RM) $(PROJECT_LIB)/$(LIB).so $(PROJECT_LIB)/$(LIB).a
 
 clean-version:
-	@sed -i.bak -E "s/(N2P2_GIT_VERSION) .*/\1 \"\"/" version.h
-	@sed -i.bak -E "s/(N2P2_GIT_REV) .*/\1 \"\"/" version.h
-	@sed -i.bak -E "s/(N2P2_GIT_BRANCH) .*/\1 \"\"/" version.h
+	@sed -i.bak -E "s?(N2P2_GIT_VERSION) .*?\1 \"\"?" version.h
+	@sed -i.bak -E "s?(N2P2_GIT_REV) .*?\1 \"\"?" version.h
+	@sed -i.bak -E "s?(N2P2_GIT_BRANCH) .*?\1 \"\"?" version.h
 	@rm version.h.bak
 
 clean-headers: