diff --git a/src/unix/posix.h b/src/unix/posix.h
index 5c74f0779..881e651f4 100644
--- a/src/unix/posix.h
+++ b/src/unix/posix.h
@@ -20,5 +20,6 @@
 #define p_vsnprintf(b, c, f, a) vsnprintf(b, c, f, a)
 #define p_snprintf(b, c, f, ...) snprintf(b, c, f, __VA_ARGS__)
 #define p_mkstemp(p) mkstemp(p)
+#define p_setenv(n,v,o) setenv(n,v,o)
 
 #endif
diff --git a/src/win32/posix.c b/src/win32/posix.c
index 38e505e20..8038fdea2 100644
--- a/src/win32/posix.c
+++ b/src/win32/posix.c
@@ -252,3 +252,11 @@ int p_mkstemp(char *tmp_path)
 
 	return p_creat(tmp_path, 0744);
 }
+
+int p_setenv(const char* name, const char* value, int overwrite)
+{
+	if (overwrite != 1)
+		return EINVAL;
+
+	return (SetEnvironmentVariableA(name, value) == 0 ? GIT_EOSERR : GIT_SUCCESS);
+}
diff --git a/src/win32/posix.h b/src/win32/posix.h
index db4ec19ec..58fd05007 100644
--- a/src/win32/posix.h
+++ b/src/win32/posix.h
@@ -32,5 +32,6 @@ extern char *p_realpath(const char *orig_path, char *buffer);
 extern int p_vsnprintf(char *buffer, size_t count, const char *format, va_list argptr);
 extern int p_snprintf(char *buffer, size_t count, const char *format, ...) GIT_FORMAT_PRINTF(3, 4);
 extern int p_mkstemp(char *tmp_path);
+extern int p_setenv(const char* name, const char* value, int overwrite);
 
 #endif
diff --git a/tests/t15-config.c b/tests/t15-config.c
index fdfa092ef..d912abb8e 100644
--- a/tests/t15-config.c
+++ b/tests/t15-config.c
@@ -26,6 +26,7 @@
 #include "test_helpers.h"
 
 #include <git2.h>
+#include <posix.h>
 #include "filebuf.h"
 
 #define CONFIG_BASE TEST_RESOURCES "/config"
@@ -217,7 +218,7 @@ BEGIN_TEST(config10, "a repo's config overrides the global config")
 	char *old_home;
 
 	old_home = git__strdup(getenv("HOME"));
-	setenv("HOME", CONFIG_BASE, 1);
+	p_setenv("HOME", CONFIG_BASE, 1);
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
 	must_pass(git_repository_config(&cfg, repo, NULL));
@@ -226,7 +227,7 @@ BEGIN_TEST(config10, "a repo's config overrides the global config")
 	git_config_free(cfg);
 	git_repository_free(repo);
 
-	setenv("HOME", old_home, 1);
+	p_setenv("HOME", old_home, 1);
 	free(old_home);
 END_TEST
 
@@ -237,7 +238,7 @@ BEGIN_TEST(config11, "fall back to the global config")
 	char *old_home;
 
 	old_home = git__strdup(getenv("HOME"));
-	setenv("HOME", CONFIG_BASE, 1);
+	p_setenv("HOME", CONFIG_BASE, 1);
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
 	must_pass(git_repository_config(&cfg, repo, NULL));
@@ -246,7 +247,7 @@ BEGIN_TEST(config11, "fall back to the global config")
 	git_config_free(cfg);
 	git_repository_free(repo);
 
-	setenv("HOME", old_home, 1);
+	p_setenv("HOME", old_home, 1);
 	free(old_home);
 END_TEST
 
diff --git a/tests/t16-remotes.c b/tests/t16-remotes.c
index 6529f0ec4..af54f297d 100644
--- a/tests/t16-remotes.c
+++ b/tests/t16-remotes.c
@@ -26,6 +26,7 @@
 #include "test_helpers.h"
 
 #include <git2.h>
+#include <posix.h>
 
 BEGIN_TEST(remotes0, "remote parsing works")
 	git_remote *remote;
@@ -34,7 +35,7 @@ BEGIN_TEST(remotes0, "remote parsing works")
 	char *old_home;
 
 	old_home = git__strdup(getenv("HOME"));
-	setenv("HOME", "/dev/null", 1);
+	p_setenv("HOME", "/dev/null", 1);
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
 	must_pass(git_repository_config(&cfg, repo, NULL));
@@ -46,7 +47,7 @@ BEGIN_TEST(remotes0, "remote parsing works")
 	git_config_free(cfg);
 	git_repository_free(repo);
 
-	setenv("HOME", old_home, 1);
+	p_setenv("HOME", old_home, 1);
 	free(old_home);
 END_TEST
 
@@ -58,7 +59,7 @@ BEGIN_TEST(refspec0, "remote with refspec works")
 	char *old_home;
 
 	old_home = git__strdup(getenv("HOME"));
-	setenv("HOME", "/dev/null", 1);
+	p_setenv("HOME", "/dev/null", 1);
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
 	must_pass(git_repository_config(&cfg, repo, NULL));
@@ -71,7 +72,7 @@ BEGIN_TEST(refspec0, "remote with refspec works")
 	git_config_free(cfg);
 	git_repository_free(repo);
 
-	setenv("HOME", old_home, 1);
+	p_setenv("HOME", old_home, 1);
 	free(old_home);
 END_TEST
 
@@ -83,7 +84,7 @@ BEGIN_TEST(refspec1, "remote fnmatch works as expected")
 	char *old_home;
 
 	old_home = git__strdup(getenv("HOME"));
-	setenv("HOME", "/dev/null", 1);
+	p_setenv("HOME", "/dev/null", 1);
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
 	must_pass(git_repository_config(&cfg, repo, NULL));
@@ -96,7 +97,7 @@ BEGIN_TEST(refspec1, "remote fnmatch works as expected")
 	git_config_free(cfg);
 	git_repository_free(repo);
 
-	setenv("HOME", old_home, 1);
+	p_setenv("HOME", old_home, 1);
 	free(old_home);
 END_TEST
 
@@ -109,7 +110,7 @@ BEGIN_TEST(refspec2, "refspec transform")
 	char *old_home;
 
 	old_home = git__strdup(getenv("HOME"));
-	setenv("HOME", "/dev/null", 1);
+	p_setenv("HOME", "/dev/null", 1);
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
 	must_pass(git_repository_config(&cfg, repo, NULL));
@@ -122,7 +123,7 @@ BEGIN_TEST(refspec2, "refspec transform")
 	git_config_free(cfg);
 	git_repository_free(repo);
 
-	setenv("HOME", old_home, 1);
+	p_setenv("HOME", old_home, 1);
 	free(old_home);
 END_TEST