diff --git a/src/intel_edison_fab_c.c b/src/intel_edison_fab_c.c
index afc9d91..052c78c 100644
--- a/src/intel_edison_fab_c.c
+++ b/src/intel_edison_fab_c.c
@@ -507,7 +507,7 @@ mraa_intel_edsion_mmap_unsetup()
         return MRAA_ERROR_INVALID_RESOURCE;
     }
     munmap(mmap_reg, mmap_size);
-    mmap_reg == NULL;
+    mmap_reg = NULL;
     close(mmap_fd);
     return MRAA_SUCCESS;
 }
diff --git a/src/intel_galileo_rev_d.c b/src/intel_galileo_rev_d.c
index 7604fd3..1febb97 100644
--- a/src/intel_galileo_rev_d.c
+++ b/src/intel_galileo_rev_d.c
@@ -44,7 +44,7 @@ mraa_intel_galileo_g1_mmap_unsetup()
         return MRAA_ERROR_INVALID_RESOURCE;
     }
     munmap(mmap_reg, mmap_size);
-    mmap_reg == NULL;
+    mmap_reg = NULL;
     close(mmap_fd);
     return MRAA_SUCCESS;
 }
diff --git a/src/intel_galileo_rev_g.c b/src/intel_galileo_rev_g.c
index da9447f..17ee77e 100644
--- a/src/intel_galileo_rev_g.c
+++ b/src/intel_galileo_rev_g.c
@@ -197,7 +197,7 @@ mraa_intel_galileo_g2_mmap_unsetup()
         return MRAA_ERROR_INVALID_RESOURCE;
     }
     munmap(mmap_reg, mmap_size);
-    mmap_reg == NULL;
+    mmap_reg = NULL;
     close(mmap_fd);
     return MRAA_SUCCESS;
 }